Most banks do not require your bank account number on the ACH file as they prefer an unbalanced file. When you setup ACH service with your bank, the bank will setup ACH service for a specific bank account. The Federal I.D. number identifies the company on the ACH header, in most cases.
However, if your bank is requesting an 'offset' record or a 'balanced' file, you can enable this by clicking on the ACH File Setup and navigating to Screen 4 by clicking through the Advanced Setup option. Once here, you will need to check the box to enable the offset, enter your ABA routing number, bank account number, and company name. (You do not need to enter an offset ID.)