Welcome to AW!
The best advice I can give you is to soak up as much information as possible on these forums. Pour over the Bewares & Background section and read up on publishers and agents. Depending on your genre and whether you're looking for a contract with one of the Big 6 (5?) houses, you'll likely need an agent, which you'll also find info on in the Bewares section.
I didn't know the first thing about the publishing world when I found AW a year ago. The info I found here helped me get that first contract. Good luck!