How do I find out what size board and bindings I need if im going to buy a snowboard?

Go by the sizing chart for your weight, not height, especially if you are heavy or skinny for your height. I am 6'4'' 250lbs (overweight) and boards that are up to my chin (166) are too small, I prefer 172. An easy way to get help for your first board if you don't know much is to go to dogfunk.com and look at their sizing charts or chat to their gear experts, but i would also shop around to other sites like sierrasnowboard.com to buy, see if they are cheaper.

Weight is probably the primary factor, but you also want to consider the type of riding you will do. Based on your weight I would say you would be somewhere between a 149 and a 156. If your going to do primarily freestyle and park riding you'll want a smaller more flexible board and would probably stay around the 149 - 151 range (I've even seen people your size in the park on 146's, but they look flimsy under their feet and are really are only good for jibbing.) For all-mountain type riding, which would include groomers, some park, and possibly some pow riding you'll want to look into something middle of the road, maybe a stiffer 151, or 154 (151 if your on the beginner side as it will be a little more maneuverable for you and 154 if you have a little more experience.) If you interest lies primarily in speed, back-country, and POW riding then you'll want a longer stiffer board (possibly with some set back if you'll be in deep.) For that I would go with something around the 156 - 158 range. I'm roughly about your size (5'5" 135lbs) and have 3 boards that I ride depending on what I want to do that particular day. I have a K2 149 for the park, I have a GNU 151 for all mountain, and I have an Atomic 156 for when I want to ride POW or I need to try to keep up with my skiing buddies. My personal fav is the 151 though. It's pretty perfect for all around riding. Hope this helped.