Hey, nice to see a new face around here. First off I'd like to point you to the Official Rules and Stuff.
There you can find guides about good RPing as well as an Example Posts, you can also get caught up on the recent happenings in the News.
Next please read the first few posts of this topic so you can see a brief overview of the current arc as well as newer rules. All the stuff posted by Nuju on those first 2 or three posts are important.
Then you can head to the Profile Pages where you can read a list of approved species as well as see example profiles for how your character should look. Also note that unless you have custom powers or foreign tech you do not require an approval and can just post and play. That should help you get started, word of personal advice is once you start find an experienced player and stick to them. It'll do wonders for your Roleplaying Abilities as well allow you to proper learn how to play the game. Don't hesitate to shoot me or any of the awesome staff of this RPG (Nuju Metru, Emzee, Friar Tuck, and Emperor Whenua.) a PM if you have any questions.
I'd like to say welcome once more and hope you have a great time here.
Also to answer your question, no you can't be a Makuta but you don't have to be a Matoran either, the list of approved species is on the Profile Pages.
Edited by Toa Onarax, Jul 19 2013 - 11:08 AM.