How do I add a additional register in my existing qb account?

Hi, dwayne6.

I'll help you on how to add a Bank register in QuickBooks Online.

Here's how: 

1. From the left menu, click Accounting.
2. Select Chart of Account.
3. Click New, then fill out an Account Type, Detail Type, and Beginning Balance.
4. Select Save and close once finished.

I've added this article for you to learn more about how you can add a bank register: Create subaccounts in your chart of accounts in QuickBooks Online.
 

You can also check these articles for more information on how to match and categorize your bank:

• Tips for Working in QuickBooks Online’s Bank Feed: Matching Transactions
• Assign, categorize, edit, and add your downloaded banking transactions

If you have questions or clarifications in managing your bank accounts, please post in the Community. We are always here to help. Take care.