Will somebody help a GML Platformer noob?

I'm a self-proclaimed noob at GML platformers, and as I understand it I shouldn't use the hspeed, vspeed, and gravity variables built in to Game Maker as they are less precise. I've attempted and failed at making my own engine using other variables, searched for and read a few tutorials, but it doesn't seem to work... at all. I can't figure out why, and I was wondering if some kind soul would be willing to download my .gmk and give me the rundown on all my shortcomings, as I'm getting nowhere on my own. I'd greatly appreciate it. Beg

Thanks in advance. Download link is here (right click save as):
http://tylorlilley.com/zomtestv0.1.gmk