When you create your object, you'll want to put in the bank details that a customer payment goes through to. Make sure these are accurate. Typically, when taking payments through BACS, you would go with the Direct Debit option as you can allow customers to make one-off payments in a simple way.

These fields follow the same pattern as your normal bank details - the one field you would use differently is Reference Instructions which prompts the paying customer to add reference details to their order should they wish.