How to add Bank account

Hi there, @mariot.

I'd be glad to help you add your bank account in QuickBooks Online. Please refer to the steps below:

1. Go to the Banking menu. 
2. Select the Link account button.
3. Enter the bank's name or bank's URL in the text box and click the magnifying icon.
4. Log in using your bank credentials.
5. Click the Continue button.
6. Choose the account you'd like to connect and select the drop-down icon beside it to assign which account you want to link your bank.
7. Select Connect.

I've also added some screenshots for your additional reference.

I've included this article that may help you with your future task about assessing your business financials: Reconcile an account in QuickBooks Online.

Please don't hesitate to let me know in the comment section if you have other questions, I'd be happy to answer it. Take care.