Motocross (side scrolling motercycle game)

Hi.

So I was asked to make a motocross game by a client, something like:


or
http://www.teagames.com/games/tgmotocross/play.php

I’m not an AS god. I’m having trouble with the basic movement programing. Attached is my (crudely drawn) attempt, it kinda works, but it has no where near the control of the above games, and I know I’m on a totally wrong track

What am I doing wrong? Is there any tutorials on a good way to do something like this?

I’m trying to figure out if I’ll be able to do this so I can tell the guy I’m working for if I can or cant do it.

Thanks in advance!