Firstly, congrats on finishing your novel. Is it your first novel, or have you completed others before this? It's kind of funny because I completed the first draft of my novel in 3 1/2 months, but I also spent hours in my room writing it and doing nothing else - literally! I haven't started editing it, yet, because I can't stand to read another word of it, lol. Maybe in a few weeks I'll be able to approach it with fresh ideas. I'm already thinking of things that can be added and changed as far as characters and plot development. But, enough about me and mine.
I wholeheartedly agree with the poster who said you need to do your own research beyond Y!A. I've done in-depth research on the publishing industry, and I know for a fact that all the information you need to know before you jump in cannot be told to you in a single post; researching this field takes hours upon hours of research and reading and seeking out reliable sources (agent and publisher blogs, and legitimate publishing articles, as well as talking to authors). Also, the reason why you shouldn't get your information from the people here (including myself) is that we're not always right. I've literally seen people constantly recommend scam literary agents and publishers. One of the publishers I see often recommend is a vanity press (better to be unpublished than published badly), and the other is owned by a person who's being sued by the State of Florida for *fraud against aspiring writers!* Yes, some people on Y!A have been recommending a scam artist to aspiring authors like yourself. If you don't know this then you'll fall for it and will be out of a lot of money and a book that no one ever reads. The only reason I know this company (actually companies) is a scam is because of the in-depth research I've done on publishing. Once you do your research then you'll know what to look for in a scam and will avoid it. There's nothing more demoralizing than knowing that you've been scammed. Some people stop writing altogether because of it.
My advice isn't regarding publishing, because you'll have to do your own research like I did, and learn for yourself that the publishing industry is wrought with scammers who are looking to take your money and that well over 90% of the people who try to get published will be rejected. Many of the unscrupulous publishers and agents advertise and can be found by doing a google search. My advice is to stay away from search engines while you're looking for agents and publishers and ignore those who have to advertise their services. Just remember that you should never pay to be legitimately published and you should never have to buy your own (overpriced) books - a sign of a vanity publisher. Also, if you find that an agent or publisher recommends an editor to whom you have to pay to edit your work that it could be just another way to get your money - the agent/publisher is getting a kickback for everyone they recommend, or, worse, they own the editing service and don't tell you. Unfortunately, I've seen people have their dreams crushed by being scammed. Many have lost the first publishing rights to their book and have to start a new one and get that legitimately published.
Okay, it sounds like you have edited your book as best you could. Great start! Now, you need to find beta readers. Beta readers are those people who will read your book and give you feedback. If something doesn't make sense then they'll let you know. They'll give you suggestions on how to make it better. Some will read for grammatical errors (you can be rejected for too many grammar mistakes). There are many things beta readers do. You can also let your family and friends to read you novel as regular readers (if they like the genre in which you've written), and to give you feedback on things that were out of place, let you know if they lost interest, or if things didn't make sense to them. You should also let other writers critique your work, because they are more in-tune with how publishable books should be written, whereas your family/friends don't. After you get feedback, you'll then start on another draft and make changes you deem necessary. It might be hard to take criticism, but think about it this way: they are here to help you make your book the best it can be so that it can be published. You don't want to here people say "it's good, you should publish it," because sugar coating things doesn't make your novel publishable. Getting feedback from independent people (who are not family/friends) will help make your book better, especially if you've never been published and don't know what to expect.
Most agents require a query letter, and some might require a synopsis, you'll have to read their guidelines because it differs per literary agency. Get feedback on your query letter, too. Your query is the deal maker. Agents and publishers will make a decision on whether or not to request you rmanuscript based on your query, and, again, once they reject you, you cannot requery for the same work. It's really that serious.
Visit the agent's website and look under their Submissions guidelines and they'll have directions on how to send your manuscript and how to format it. Some agents will allow the first few pages of your work along with the query. Do you know why? Because you have to catch the readers' attention within the first few pages. That means you have to have some kind of conflict happen that will keep the reader reading in the very beginning. I've seen agents request the first 7-10 pages, so let the number of pages they request (if any) be your guide.
Just keep in mind that if you are one of the lucky few to find an agent or publisher to publish your work then it will take a while before your book is released - it can be upto 2 years after you sign the contract. Also, querying can be a lengthy process. Some agents send out rejections or request partials within days, while others can take months. One more thing, query only a few agents at a time. This will allow you to make changes to your query letter or manuscript if you begin getting too many rejections, and then you can send out a revised version to other agents. Just remember that just because you've written a book does not mean it's publishable. Unfortunately, most people's books are not publishable. Good luck!