When you have located a business partner, click it and the details will show in a panel (so called "drawer") on the right hand side. Details can be maintained directly in the fields.
By clicking the secondary actions icon additional actions may be possible.
Edit Business Partner Name
Delete
Restore (if deleted)
Permanently Delete (if deleted)
With a business partner drawer open, locate the section for Bank Accounts under the Financial tab.
Click the "Add" + icon and select a bank account to add the bank account to the business partner.
With a business partner drawer open, locate the section for Contact Persons under the Main Details tab.
Click the "Add Contact Person" + icon and fill in the given fields to add a contact person to the business partner.