First, how much you weigh has a lot to do wit how much and what you eat.
Second: Lifting weights or lifting your body is bot lifting for the muscles. The issue is that doing 100 pushups is like benching 50 pounds: after a while, it will do nothing for your muscle size. You need to make certain exercises harder so performing them in a lower rep range is challenging. Do basic pushups build muscle? Only for a beginner. Do things like handstand pushups, one armed pushups, one legged squats, front levers etc build muscle? Yes.
My advice to you would be to get Ross Enamait's ebook 'Never Gymless', it's cheap and contains everything you will need for at least the next year.
EDIT: Please realise that a lot of the guys you look up to are genetically blessed. If all you care about is looks, just o to the gym; it is by far the easiest way to do it.