I hope the installer secured the wireless side. Most installer do not, they leave the wireless open, no security. I don't know how may I have ran into like this, I lost count.
If you are connected to the wireless router/modem. You need to turn on file and printer sharing on your desktop computer. Then select the printer and make it shareable. On your laptop use add a printer wizzard and follow the instruction for setting up a network on shared printer.
Should be good to go.