This will be available in TurboTax around the middle of February.  Amending is a simple process in TurboTax.  I will provide instructions below.

You will need to wait until the IRS receives and processes your original return. Wait until you receive the refund on your original tax return (or your check clears if you had to send a payment).

This article shows you how to amend your 2018 tax returns prepared in TurboTax.  If you used the desktop version of TurboTax, skip to step 6.