OLS Regression hands on code ...help

Thanks pylang for your reply . But i am typing each sentence
I am actually lost and unable to find out why it is throwing me an error

my code snippet is as below :-1:

###Start code here
X = dataset[“RM”]
Y = dataset[“target”]
###End code(approx 2 lines)

import statsmodel.api as sm

X= sm.add_constant(X)

then the error pops up


NameError Traceback (most recent call last)
in
----> 1 X= sm.add_constant(X)

NameError: name ‘sm’ is not defined


NameError Traceback (most recent call last)
in
----> 1 X= sm.add_constant(X)

NameError: name ‘sm’ is not defined