Well, if you want to go the professional route you should invest in finding an agent. They can be incredibly helpful, but difficult to find the right match. An agent/author relationship is like marriage so finding the right one could takes months, even years. There's plenty of sites to help you narrow them down: Agentquery, QueryTracker, etc. Once you find one they will then pass it along to editors in the publishing houses. You can skip the agent and submit straight to publishing houses, but those response times could take months and it's harder to get your foot in the door that way. It's an agent's job to know these editors so they know who to pass along a manuscript to. I'm still in the process of searching for an agent so from there I don't know the entire process.
You can also go the self-publishing route, but don't expect too much success unless you're willing to put in 110%. Like agent sites, there are plenty of self-publishing sites: Lulu, iUniverse, etc. But know that you'll have to spend money to make money in the self-publishing world.
Overall, all writers have to do is write the novel, polish it up, and submit. The agents, editors, and publishing people take it from there. Writers, from what I've read, don't have much to do with the actual publication of the novel. They're just given revisions to do and are told about the process.
Hope this helps and sorry for the elongated answer.