Brand new at this. How and where do I enter a personal check transaction, I had to pay $10 for a background check.

Welcome to the Community, @tonig_wi54.

You can manually add this expense transaction to QuickBooks Self-Employed (QBSE), then categorize it to the right category.

Here's how:

1. Go to the Transaction menu at the left tab.
2. Click  Add Transaction. 
3. Add all the necessary information. 
4. Browse the Select a category menu and choose the category that suits this expense.
5. Click the Save button once you're done.

See this article for more information: Manually add transactions in QuickBooks Self-Employed. Also, here's more information on how to categorize and edit transactions in QuickBooks Self-Employed. 

I'm always here if you need more help with your transactions. I'm always here to assist. Have a wonderful day!