I have a train_data which holds information about Stores and their sales. Which looks like this

I want to build a multiple feature linear regression to predict the 'Sales' on a test_data, by using 'DayofWeek', 'Customers', 'Promo'.
How do I build a Multiple Linear Regression Model for this, preferably by using SKlearn.
edit: here's the link to the dataset I am using, if anyone is interested : https://www.kaggle.com/c/rossmann-store-sales
This is what i've tried so far.
import pandas as pd
from sklearn import linear_model
x=train_data[['Promo','Customers','DayOfWeek']]
y=train_data['Sales']
lm=LinearRegression()
lm.fit(x,y)
For which i am getting an error saying 'LinearRegression not defined'.
from sklearn.linear_model import LinearRegression