Refer to the section on "Purchase Invoice for a stock item".
Procedure for data entry is the same for Purchase of a stock item, except the heading "Type", needs to be changed to GL, as demonstrated in the screenshot below:

The code then becomes the General Ledger account number. For example, Advertising expenses. (Once again, the headings required for data entry can be set as necessary).
Debit Expense
Debit GST
Credit Accounts Payable (Creditors)
Refer to the section "Purchase Invoice for a stock item" for further processing options.