Whats a really good first park board. I wanna try some jumps and some rails.?

it depends what you're looking for. like the other guys posted, the ride DH and DH2 and forum destroyer (and other similar boards) will have great pop and be great for jumps. If you want something more flexible, go with the Ride Kink. If you want something REALLY flexible check out the K2 WWW or Rome Artifact rocker. If you want something kinda in between with good pop and good flexibility, check out the K2 parkstar which is what i recently bought and i love it! Also, most companies make similar boards so just go to a specific website of a brand you like and read the description of their boards. If you don't feel like doing that though, I gave you a few good ones to check out. There are like 20 high end brands out there and its not a big deal which one you choose if you know which ones the good ones are.

Forum Destroyer, it has so much pop. However, thats my personal preference. I reccomend that you go to a shop (with intentions to buy a snowboard) and see what they reccomend.