You can create an expense transaction to add a charge to your credit card in QuickBooks Online. I'll show you how.
Click the + New icon.
Select Expense.
Choose a payee from the Payee dropdown.
In the Payment account, select your credit card account.
Fill in all the necessary information.
Once done, hit Save and close.
Once you're ready to make payment to your credit card charges, you can read this article for a complete guide to recording them in QuickBooks Online: Record your payments to credit cards.
You're always welcome to post again if you need further assistance recording transactions in QBO. I'll be here to help you.