It seems like you're attempting to manually add a bank account in QuickBooks Online. If that's what you're trying to accomplish, I can walk you through the steps.
Here's how:
From the left navigation menu, click on Accounting.
On the Chart of Accounts page, click on the New button.
In the Account Type field, choose Bank.
In the Detail Type field, pick the appropriate bank account type (For example; Checking, Savings).
Enter a name for the bank account in the Name field. You can also add a description for this account
Select the currency for the bank account in the Currency field.
Enter the opening balance for the bank account in the Balance field.