Select the form 1040X, check year you are amending.  Your 1040X will then populate with original return information - THEN - correct tax return. The correction will then populate on 1040X.  Type in your explanation for changes made.   Form 1040X should now be in your list of Forms In Use for printing.  Don't forget to print the Form 1040 and any supporting forms/schedules that were corrected to mail with your 1040X.