How does p90x work once you begin it?

if your fat when you begin doing the p90x do you start off with cardiox for the first month untill you loose all your wieght and then do ab ripperx... or do you do cardio x and ab ripper x at the same time for it to get you buffed out but in good shape? which one first i have the videos but in a flashdrive and i dont know how to begin it? does anybody know how and thanks?