Muscle Mass Workout

I normally work one day on chest and arms, the next on legs, then I do back and abs. But for some reason it doesn’t feel like im doing something right.

hey,
I don’t workout using the one body part style, it is common and preferred by some. I like to hit the weights, three days a wk, the other 2 or 3 days some cardio.
For size, do reps in the range of 8-10, or 10-12. change up your weights every 4 wks or so, as the muscle needs to be tricked. If you could hit 3-5 sets, you would be working out hard and start seeing something soon.
I feed my muscles after a workout with a smoothie, with 40 grams of protein. Remember to take it within 30 min of working out for best absorption into the muscles.
i get my stuff from the link below, they have a forum page with some good recipies and workout discussions. The oreo smoothie is the best!

I dont want to gain 20-30 lbs of muscle, just bulk up a little bit.

Not really, you can do exercises to strengthen muscles such as your abs and increase muscle endurance. But to put on any noticable amount of muscle requires weight training.
I wouldn’t worry about putting on 20-30 lbs of muscle.
Packing on muscle is a lot harder than the average person seems to think (check all the people saying – "I want to do this or that but I’m afraid I’ll end up with muscles"). To add muscle you need to be eating extra calories, a high proportion of them being protein. You’ll also need to be doing weights several times a week for months before you start to see any gains. (more…)

I workout 2 hours a day and don’t gain much.

2 hours is too little for 15 year old, you are young so you recover faster then older people. You should work out at least 4 hours a day.

Wall Squats

Using the Elliptical

those two are basically the exercises that I have done to gain my muscle mass back (more…)