It looks like you could be trying for one of two things, so I will answer both:
(Note that I'm assuming text is your variable name.)
1. Try using the .NET function String.Split like this:
Dim strSplitString = text.Split(";"c)
For Each strOutput In strSplitString
Console.WriteLine(strOutput)
Next
To use String.Split, use the Split method of the string you want to split and pass the character you want to use as the separator as an argument. This produces a string array that you can then irritate through with For Each . . .
Note that if you want String.Split to accept a string as a separator, you must also specify how many strings it may include and whether it may include blank strings.
Dim strSplitString = text.Split("750", 750, StringSplitOptions.RemoveEmptyEntries)
2. Try using the .NET function String.SubString to retrieve the first 750 characters of your string.
Dim strSplitString = text.SubString(0, 750)
Console.WriteLine(strSplitString)
ToString()is a method, so it needs the brackets to be included on the second line.ToString()on an array returnsSystem.String[]. Don't call this and iterate the array.