2 Answers

 It should have some gas in it.  As many times as I've started my chainsaw, I've never even noticed if the button was full or not. I just see gas in it. Just prime it. If it still does not start, unchoke or choke it. If it still does not start, check the oil and make sure the blade is in the locked position. If it still does not start, that's chainsaws for you. They're a pain to start when you need them. 

As  you push the button gas it pushed through and the amount is not your control.  Although if you break down and "READ THE DIRECTIONS", it might tell you to set throttle,  push twice and pull on rope or however.  If you don't have manual for  directions then google and find your brand.  Last but not least check, clean or replace the spark plug.  My point is with things like this you usually have to do a certain amount of prep.  If all fails take it to a repair shop.