If you just recently efiled, you need to wait to see if the return is accepted or rejected. If it's rejected, then that's the easiest situation, since you can just make the changes and resubmit the efile. If it's accepted, however, then the only way to make changes is to prepare a formal amended return Form 1040X.
If you were due a Federal refund with the original return, then most forum helpers recommend to wait until you receive the Federal refund before amending. Likewise if you owed taxes due, wait until the return has fully processed. It's possible the IRS might change something.
FAQ: How do I amend a return I already filed?