First, I would wait until your return has been accepted. If it is rejected, you can go back and enter those forms, if necessary.
If it is accepted, then you will need to prepare an amendment to add those forms/information.
The amendment forms will not be available until the Form 1040-X is finalized.
The IRS does not accept e-filed amendments so you would need to print out and send in that amendment.
The directions for filing an amendment will be here once the Form 1040-X is finalized.
https://ttlc.intuit.com/replies/3288565
