I filed my 2015 return directly to IRS, can I amend it using turbo tax?

[Carl]

If you did not originally prepare and file your return with TurboTax, then it's a LOT of work to file an amended return with TurboTax.
First, you have to prepare your return "exactly" as originally filed with the IRS. Then you have to select the "print and file" option and actually print the return, so the program will "think" you already filed it with the TurboTax program. Then, and only then can you amend the return.

On top of that, you can not e-file an amended return. The IRS says so. YOu have to print it, sign it (both the 1040 and 1040-X) and mail it to the IRS.