From YoYoGames Wiki Game Maker Scripts are used in Game Maker to execute code. A Game Maker script is basically a function, capable of taking arguments in, and returning a certain return value. The advantage of scripts over regular pieces of code is that they could be performed more than once, saving file size, memory, and also making the code simpler to read, understand, and edit.

This is a tutorial website for gamemaker! It is very helpful and can teach the basics quickly but thoroughly.

SpriteLand is a resource for your graphic projects. We have plenty of free graphics/sprites for use in your use. We also have fun animations, games and webcomics for you to enjoy. Play and have fun with our collection ofgames; immerse yourself in the onlineanimations andwebcomics; and enhance your own projects with thegraphics section.

Overall this guy teaches you how to use the basics of Game Maker while showing you some simple code that could improve the way you make a game!
http://forums.tigsource.com/index.php?topic=3251.0