Amended returns cannot be e-filed, so when Form 1040X becomes available you'll need to print and mail the return to the IRS. Form 1040X for amended returns won't be available until late January or early February 2018 so you will need to wait until that form is ready before you print and mail the return.
To check back and see if Form 1040X is available, click on How to amend (change or correct) a return you already filed.