If the volume of invoices is such that you do not mind doing it manually you can use Manual Invoice Entry which should appear on your A/R-Daily menu. This will let you enter individual invoices into the system for each customer's open balances or individual invoice records for each detail open item each customer has. Your choice how much detail you enter.
You will have to enter an offsetting G/L account to make each invoice record balance in the financial system and you need to select an appropriate account to use -- probably not a revenue account but your financial staff should be able to advise you.
If the volume is too high then you can follow the instructions given for using the "z-file" process.