Ok, this can be any number of things....
1. Have you shared the printer on the host computer?
2. If you're using wireless networking, you may need to make sure that your laptop is in the same workgroup as the host computer.
3. You can't just add the printer driver on your laptop and expect it to find it. Go into your control panel, click printers, then use the 'add a printer' wizard. You'll be looking for a network printer, not a local one. It should pull up a list of computer names. Track down the host computer's name, and double click it. This should then reveal the printer you need. From there, just follow the prompts.
All of this assumes that you're using windows. If not, I really can't help you, as I've only done sysadmin on windows systems. Also, there are a ton of things that can go wrong, and it's a lot easier to troubleshoot in person, I just jotted down a few things off the top of my head. If you have any more details, post them, including a step-by-step list of what you've done so far. That'll help us find out what you've done, and what you still need to do.
Hope this helps.