How do I file an Amended Return with Turbotax Desktop?

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

Continue the tax return that you need to amend -

Click on Federal Taxes (Personal using Home & Business)

Click on Other Tax Situations

Under Other Tax Forms

On Amend a return, click on the start button