Hello there, summer,
If you have a QuickBooks Payments account, you can connect it directly to QB. Here's how:
Sign out of QBO then sign back in to see the QB Payments feature.
Now that you have connected your account, check these articles on how to record payments:
However, if you have a third-party merchant's account, check with them if you can integrate it with QuickBooks.
I'll be here if you need further assistance.