I have one transaction that my quickbooks online did not pick up, i dont know how to add it manually

Hi there,

Welcome to the Community. I'd be more than happy to assist you with adding your transaction to QBO. 

There are several ways on how you can manually enter a transaction in QuickBooks Online. You can do it by clicking the Plus (+) sign, through the register, or on the transaction screen.

To learn more about how to navigate and create transactions, you can visit the article below that shows video tutorials: https://quickbooks.intuit.com/tutorials

If you want to enter a transaction directly to the register, please follow these steps:

1.     Click the Gear icon.
2.     Below Your Company, select Chart of Accounts.
3.     Choose an account and click View register.
4.     Click the drop-down arrow below the Date column (see screenshot below).

You can also add transactions manually by clicking the Plus icon and selecting the transaction type. I'll attach a screenshot below for reference: 

Give this a try and let me know if you have questions. I'll be on standby in case you need further assistance.