Amended returns have to be printed and mailed. They can't be e-filed per IRS regulation. It is recommended to wait until the IRS has accepted your initial return and you have received your federal refund before you amend the return. And the filing instructions page that prints with the return will tell you what needs to be included. If you have done the amend steps and you need to get back in and print the return, the steps to do so can be found below.
Detailed Instructions for TurboTax Online:
And you can find a list of frequently asked questions, about amended returns, here Form 1040X, Amended U.S. individual Income Tax Return, Frequently Asked Questions