P90x Videos Online P90x Questions? Help! Thanks?

P90x questions? Help! Thanks? - p90x videos online

Hello, I am thinking about doing P90X system.
I really do not know much about him, and I just downloaded online video ..
I have the video finished chest and back, and I could not even half. I made it, at least in the video, and if I had to do "Ripper AB x" can not even lift my legs were so tired. Not even a pull-up bar, but my resistance bands and a door. is better, and it pays to stay? BTW I really have not much time to do it or simply care plans, I'm a mess Ahhh ... Someone could me some advice / tips? And that training is the hardest? BTW I'm 17th Thanks