Go to Setup > Automated Payments > Add Payment Method
Click on Add Manual Payment Methods
Add the details about your payment method, such as cash or check, etc. If you are adding 'Bank Transfer' as an option, add your bank details in the 'Instructions' field.
Save your changes!
Important note: If you do not want your members to be able to choose this manual method as an option, check the 'Hidden' box. This will keep it for internal use only (accessible by going to the Member's Profile > Payment Method > Change Payment Method).