Platformer

hey im quite new at flash and know a bit but i was wondering if someone could help me make a game like poptropica http://www.poptropica.com/ and what i really need help on is the fact that when you hold down the left key an animation plays of him moving left, when u hold down the right key an animation plays of him moving right, the longer you hold the space bar, the higher he jumps(can their be a limit) and when theirs no key being held down, he just stands their, but if hes in midair he’l fall down then stop