Can't Get Notebook to Print from Desktop Base Printer

I took a highschool friend to my ex-boss' house to set up his wireless network at home.
He set up the desktop as the base with the router, etc.
Then set up the 2 "work" laptops.
Then the ex-boss bought a new printer and set it up with the desktop (can print fine) but can't print with his laptops.
The kid moved and is no longer accessible and I dont want to leave the ex-boss hanging.
Is there someone who can tell me, or somewhere I can find step by step process how to tell him to "connect"
ps
If he can print directly to the printer from the desktop, I have a feeling he set it up as a non-networked printer. Would he need to change that first?
Linda