You should not change or add anything until your original return is accepted (if they reject it you can fix it and resend it) and fully processed and you get the first refund or pay the tax due. Then you can amend it. Do not enter or change anything until after you start the amended return. If you have added or changed your return you need to take out any changes and put your return back to the way it was when you originally filed it.
How to amend an Online return https://ttlc.intuit.com/replies/7276596