But, not to belabor that point, I'm going to assume you know your craft and have written something incredible that deserves to be published. So, here's a few simple ideas (because there are entire books written about this!) to think about:
1) If you're looking to publish in the national market you'll need an agent. And the best way to find one is to ask other writers who write in the same genre as you or attend writer's conferences where they have agents/publishers come to speak. Many offer you one-on-one time to pitch your idea for an additional fee. Otherwise, there is a resource online but you'll have to do your research. If your writing is geared to a very specific niche (like Christian romance or how to yo-yo), you may not need an agent but just have to track down an appropriate publisher and can just follow the publisher's guidelines which they have on their websites. Remember that competition in most areas is fierce and be prepared for rejection--so try and look at it as a chance to improve.
2) Contests can be a great way to get noticed as well. Different writer's groups and magazines (i.e. Romance Writers of America, Writer's Digest) will have contests that you can get some attention for entering. There are numerous online contests and blogs that allow you to showcase your work, get feedback and gain status by how many followers like what you do.
3) Network, network, network. If you have a large group of writer's that you know, then you have a large group of agents, publishers and information that THEY know. Now I'm not suggesting that you go join some group for the sole purpose of picking someone's brain. I hate it when someone finds out I'm published and instead of getting to know ME, they just want to know what I've learned through years of agony and effort. Just remember, you need to have a support system of people who understand why you write, who'll support you and then cheer you on when you do find success. So start now.
4) Consider what you're trying to publish. Is it an exciting suspense novel with universal appeal or a memoir about how you grew up on a farm. If it's the latter, then you may want to consider self-publishing. Not that a well-crafted book about your life couldn't be interesting, but unless it has a real widespread appeal (like a cancer survivor story or some other angle), a publisher won't touch it. But you can self-publish through several companies for a relatively small fee (around $600 to set up and then pay for each book). Consider groups like AuthorHouse or Morris Publishing. There are hundreds and again you'll have to do your research.
So that's it in a nut shell. Good luck and get back to writing!