Not sure if a General Journal is the approach they meant....are you sure they said this?
The proper way is to enter a Bank Tranasaction...Transactions >> Financial >> Bank Transaction.
In the Option field, select Receipt.
Enter the date, Chequebook ID, and a Receipt Number (Eithre from a lodgement book, or the transaction number from your bank statement). Then enter the Recevied from, description, and amount fields.
In the scrolling window at the bottom, distribute this receipt transaction in your GL. The Debit will default to the GL account associated with your Chequebook ID....and you choose the Credit.
Using this method, you get a valid transaction in your bank module that you can reconcile if you use bank reconciliation.
Hope this helps.