BAZN, there's no one path to publication, but there are some which work more often than others. Self-publication of fiction is not among them. Neither are contests for novel-length work.
For a first novel in the YA genre, you word count should probably not exceed 80,000. You may have some trimming to do.
Your next step is to revise and polish that 80,000-or-less-word version until it can’t possibly be improved. This may take years, literally. If you merely have a completed novel you've gone over a few times, it's not ready, even if it's pretty damned good. It has to be better than good to compete.
Put it away for six months, no peeking, while you do your homework. You can jot yourself notes, but you literally cannot read any of it. You will be amazed at both the ideas you get for improving it and the flaws and weaknesses which fresh eyes see six months later.
While you let that time pass, identify agents who have recently sold other novels like yours. ("Recently" means in the last two years or so.) Visit large bookstores. Note titles, authors, and publishers of the books in your genre.
Get online and try to determine which agent sold each book. (Search “Full Title” + agent. Also try “Author Name” + agent.) You can find other agents seeking work in your genre through “Writer's Market” and “Literary Marketplace” (US) or “Writers’ & Artists’ Yearbook” (UK). Check the publisher listings, too, which will include “agented submissions only” or not. (Maybe you don’t even need an agent.)
Research each agent. Find websites with career history, sales, personal bio, blogs, AAR membership, etc. Determine whether they prefer email or regular mail for queries. Figure out who’s a good fit for you. Don’t be afraid to aim high. The worst that can happen is they say no. Your research should include a visit to Preditors and Editors.
Write a one-page query letter, tailoring it to individual agents based on the information you got from research, and send it to the few agents you'd most like to represent you. If the query letter is really good and you've done your homework well, at least some will ask for a partial or full manuscript. If none does, rewrite the query before sending out the next batch.
Remember, reputable agents charge the author NOTHING up-front. Some agents may deduct the costs of doing business (copies, mail, phone) from your first check, but nobody legitimate needs any money to get started.