Few different ways. Here's two...
-You put either all of it, or a representation of the best portions of it, online. Then contact Talent Management, or any editors whose emails you happen to have, send them the link, then hope they have time to read a little bit of it.
-Go to a con, with a copy of the gn, or a card with a link to a online sample.
Remember, people that work in comics reads TONS of stuff everyday, so it can be difficult to ask them to read your samples, when you consider that every aspiring writer/artist is also sending them stuff every day. There's no exact science; you just have to be persistent and not give up. Frustrating, I know. But it's the truth. Almost everyone that's been successful in comics has had to go through the same grind you're going through now. Just gotta stick with it.