Traditional approach to commercial publishing: get an agent, who will present your work for you to publishers. Forget sending directly to publishers, they get enormous piles of manuscripts and yours will go in the circular file unless it's coming from an agent.
The other approach is self-publishing. The two sites I'd suggest for this are
Lulu and
CreateSpace; they both will publish your book and provide resources for marketing (or if you just want a few copies for family & friends, they'll do that too). The latter one is an Amazon.com venture.
Avoid vanity presses - they'll take your money and you'll end up with a pile of low quality product. If you're lucky.
The other information you need is how to package your manuscript; go to your local library or bookstore and look for the Writer's Market, which provides a lot of useful information on manuscript preparation. Another good resource is Writer's Digest, a magazine that's widely available. But watch out for the vanity press ads in the back.
Finally, pursue publication because you love to write and are driven to do so ... writing books is no way to make a living so you'll not be quitting your 9 to 5 job.