Go to www.writersdigest.com for a ton of information
You first need to decide if it would be in your best interest to seek out a literary agent instead of a publisher. Agents are the best at finding the right publisher for your work, and getting you the best deal (most money), as well as making sure your rights are protected, etc.
In most instances, you'll want an agent.
www.writersmarket.com has lists of agents seeking new writers. You'll need to purchase a subscription, but if you've actually written an entire novel, spending a few bucks to find an agent / publisher is well worth it.