It’s not too complicated. Just amend it when it’s available, usually towards the end of February, or you can add them to next year’s return.
If you filed, it is like dropping it into a mailbox - you cannot get it back.
You'll have wait until your return is either accepted or rejected.
See this TurboTax FAQ for help with amending.
You can check the status of your amended return here, but allow 3 weeks after filing for it to show up.
Just to be clear. The first answer by C-rose3217 was wrong. You can NOT enter it next year. You have to report all your income on the same year tax return. So if your return was accepted without it you need to mail in the Amended 1040X return to add the missing info and correct it.