Welcome yoseph,

as Simulacra mentioned, the Wiki is the best place to get information, it has a Getting Started section, which I have just seen is not that relevant and needs fleshing out.

Perhaps the best info for you now is the Macros section.

The basic tenets are that you have one active instance of wow know as your main, brain, targetter etc and all the others, whether there is 1,2, 5 or 10 are followers.

The followers must follow (/follow) the main character... if you try to actively move the main and followers at the same time, they will diverge and you will feel like you are herding cats.

In order to kill things you must assist your main character (/assist) and then pass the keys to both windows for the spell you want to cast.

This is all, of course, at the most basic level. Read the wiki it is a distillation of the information in these forums... don't both with the stickies, they are out of date and are in the process of being consolidated into the wiki, after which they will be removed (we have to get the community to use the wiki more).