If you used the Desktop program you first need to update your return with the filing status so it knows it was filed and accepted.
Open your return and go up to menu item
File>electronic Filing>Check Electronic Filing Status
Then save your return. Then close and reopen the program. Then update the program before you open your return, go up to Online->Check for Updates.
And before you amend you should have saved a copy of your file so you have the original. Go up to File->Save As and give it another name.
If you don't see a button for Need to Amend a Filed Return? on your home screen then you can get to it here. Go to:
Federal Taxes -or- Personal (for H&B)
Other Tax Situations
last section, Other Tax Forms
Amend A Return - Click the Start or Update button
