Where do i fill in the information about how the client paid? like check # and date received?

I can help you enter additional details of your client's transaction, jcrooter1. 

QuickBooks Online has an option to enter checks that allows us to enter a Check No. and Date received. For QuickBooks Self-Employed, if we are using an invoice in recording client transactions we can manually mark it as paid and enter the payment in the Transaction page. From there we can enter the Check # and the Date we received in the Notes field. 

Here are a few articles that help us in categorizing transactions and other ways in receiving payments. 

Let me know if you need anything else. Thanks!