Sorry , I think, I read wrong.
Are you tring to connect wirelessly to the printer on the desktop and the printer is connected to the desktop thru usb or something?
Quoted from MS website:
Sharing a printer
If you have a printer attached to one of your computers, you can print to it from any computer connected to your wireless network. To share a printer, follow these steps:
1. Log on to computer that has the printer attached to it.
2. Open Network and Sharing Center by clicking the Start button , clicking Control Panel, clicking Network and Internet, and then clicking Network and Sharing Center.
3. Click the arrow button next to Printer sharing, click Turn on printer sharing, and then click Apply.
4. Click the arrow button next to Password protected sharing, click Turn off password protected sharing, and then click Apply.
Note
If you have password-protected sharing turned on, people will need a user account with a password on your computer to access your printer.
To access the printer from any computer on the network, follow these steps:
1. Open Network by clicking the Start button , and then clicking Network.
2. Double-click the icon for the computer that has the printer attached to it.
3. Double-click the icon for the printer. Windows will automatically add the printer to your computer and install the printer driver.
Troubleshoot network printer problems
Sorry again and goodluck