1. I need to be able to move my token.
2. The token starts in the square 1.
3. If the token is on squeared 1 and is moved 3 then the token is on square 4.
4. A player can win the game.
5. The first in reach the square 100 is the winner.
6. You can't over-square the board. If you do it your position will be remind to the previous one. (97 + 4 = 97)
7. The moves are based in a roll dice between 1 and 6.
8. The player roll the dice, then move the token.

Keeping all this in mind I did this.

using System;
using System.Collections.Generic;

namespace Snakes_and_ladders
{
    class CBoard
    {
        private int[] board;
        List<CPlayer> players = new List<CPlayer>();

        public int[] Board { get => board; }
        public CBoard()
        {
            // Se crea un tablero de 100 celdas por defecto. 
            board = new int[100];
            Array.Clear(board, 0, board.Length);
        }

        /*
        * Funcion para crear Ladders y Snakes. 
         * Se cambia el valor del array en el index [i-1] siendo i la key del diccionario. 
        * el valor que se guarda en ese index corresponde al valor del tablero donde se 
         * movera el jugador en caso de caer en dicho Index.
        * 
        * Ex: Key => 2, Valor => 10 implica que existe una escalera que va desde la celda 
         * 1 a la celda 9 del tablero.
        */
        private void createSnakesOrLadders(Dictionary<int, int> dataDict)
        {
            foreach (KeyValuePair<int, int> data in dataDict)
            {
                board[data.Key - 1] = data.Value - 1;
            }
        }
 

        /*  Sobrecarga de constructor por defecto
        *  Crea un board de AxL + añadir escaleras y serpientes.
        */
        public CBoard(int altura, int largo,
            Dictionary<int, int> ladders = null, Dictionary<int, int> snakes = null)
        {

            // Como minimo es necesario un tablero de 2x2.
            if (altura < 2 || largo < 2)
                throw new Exception("La altura y largo necesita ser al menos mayor a 1.");

            // Tamaño inicial del numero de ladders y snakes en el tablero.
            int ladderSize = 0;
            int snakesSize = 0;

            // Si el tablero no es null, guardamos el numero real de ladders y snakes.
            if (!(ladders is null))
                ladderSize = ladders.Count;

            if (!(snakes is null))
                snakesSize = snakes.Count;

            // Creamos el tablero, con valores a 0.
            board = new int[altura * largo];
            Array.Clear(board, 0, board.Length);

            // Si el tamaño total del numero de ladders y snakes es menor que la mitad del tablero
            // Se crean los ladders y snakes en el tablero. Sino, se lanza la excepcion.
            if ((ladderSize * 2) + (snakesSize * 2) / 2 < board.Length)
            {
                if (!(ladders is null))
                    createSnakesOrLadders(ladders);

                if (!(snakes is null))
                    createSnakesOrLadders(snakes);
            }
            else
            {
                throw new Exception("La suma total de Snakes y Ladders no puede superar el 50% del tablero.");
            }
        }
    }
}

using System;
using System.Threading;

namespace Snakes_and_ladders
{
    class CPlayer
    {
        int[] board;
        private int position = 0;
        private string nickName = null;
        private int diceResult = 0;
        private bool winner = false;

        public int Position { get => position + 1; }
        public int DiceResult { get => diceResult;  }
        public string NickName { get => nickName; }
        public bool Winner { get => winner; }


        public CPlayer(string nickName, CBoard board) {
            this.nickName = nickName;
            this.board = board.Board;
        }

        public void Roll()
        {
            // Se espere 30 milisegundos para cambiar la semilla del random.
            Random rnd = new Random();
            Thread.Sleep(30);
            diceResult = rnd.Next(1, 7);
        }

        public void Move()
        {
            // Move the player N dice cells.
            if (position + diceResult < board.Length)
                if (board[position + diceResult] == 0)
                    position = position + diceResult;
                else
                    position = board[diceResult + position];

            if (position == board.Length - 1)
                winner = true;
        }
    }
}

1. I need to be able to move my token.
2. The token starts in the square 1.
3. If the token is on square 1 and is moved by 3 then the token is on square 4.
4. A player can win the game.
5. The first who reaches the square 100 is the winner.
6. You can't over-square the board. If you do it your position will remain the same. (97 + 4 = 97)
7. The moves are based on a roll dice between 1 and 6.
8. The player rolls the dice, then moves the token.

Keeping all this in mind as I did.

using System;
using System.Collections.Generic;

namespace Snakes_and_ladders
{
    class CBoard
    {
        private int[] board;
        List<CPlayer> players = new List<CPlayer>();

        public int[] Board { get => board; }
        public CBoard()
        {
            // A 100-cell board is created by default.
            board = new int[100];
            Array.Clear(board, 0, board.Length);
        }

        // Function to create Ladders and Snakes.Se changes the value
        // of the array in the index [i-1] being i the key of the
        // dictionary.the value that is saved in that index corresponds
        // to the value of the board where the player moves in case of
        // falling into said Index.
        //
        // Ex: Key => 2, Value => 10 implies that there is a ladder that
        // goes from cell 1 to cell 9 of the board.
        private void createSnakesOrLadders(Dictionary<int, int> dataDict)
        {
            foreach (KeyValuePair<int, int> data in dataDict)
            {
                board[data.Key - 1] = data.Value - 1;
            }
        }

        // Default constructor overload
        // Creates an A x L board by adding ladders and snakes.
        public CBoard(int altura, int largo,
            Dictionary<int, int> ladders = null, Dictionary<int, int> snakes = null)
        {

            // At a minimum, a 2x2 board is necessary.
            if (altura < 2 || largo < 2)
                throw new Exception("The height and length need to be at least greater than 1.");

            // Initial size of the number of ladders and snakes on the board.
            int ladderSize = 0;
            int snakesSize = 0;

            // If the board is not null, we save the actual number of ladders and snakes.
            if (!(ladders is null))
                ladderSize = ladders.Count;

            if (!(snakes is null))
                snakesSize = snakes.Count;

            // We create the board, with values set to 0.
            board = new int[altura * largo];
            Array.Clear(board, 0, board.Length);

            // If the total size of the number of ladders and snakes is less than half the board
            // ladders and snakes are created on the board. If not, the exception is thrown.
            if ((ladderSize * 2) + (snakesSize * 2) / 2 < board.Length)
            {
                if (!(ladders is null))
                    createSnakesOrLadders(ladders);

                if (!(snakes is null))
                    createSnakesOrLadders(snakes);
            }
            else
            {
                throw new Exception("The total sum of Snakes and Ladders cannot exceed 50% of the board.");
            }
        }
    }
}

using System;
using System.Threading;

namespace Snakes_and_ladders
{
    class CPlayer
    {
        int[] board;
        private int position = 0;
        private string nickName = null;
        private int diceResult = 0;
        private bool winner = false;

        public int Position { get => position + 1; }
        public int DiceResult { get => diceResult;  }
        public string NickName { get => nickName; }
        public bool Winner { get => winner; }


        public CPlayer(string nickName, CBoard board) {
            this.nickName = nickName;
            this.board = board.Board;
        }

        public void Roll()
        {
            // Wait 30 milliseconds to change the random seed.
            Random rnd = new Random();
            Thread.Sleep(30);
            diceResult = rnd.Next(1, 7);
        }

        public void Move()
        {
            // Move the player N dice cells.
            if (position + diceResult < board.Length)
                if (board[position + diceResult] == 0)
                    position = position + diceResult;
                else
                    position = board[diceResult + position];

            if (position == board.Length - 1)
                winner = true;
        }
    }
}