How to build muscles without going to buy equipment?

[v3ng3nc3]

I'm 14 years old and want to focus on Arms ( Shoulder,Bicep,Tricep ), Legs( Thighs, Calves ) and maybe back.
I can't go out and buy equipment but I do have a schoolbag loaded with books from last year so I can just add or take books to change weight.
I see myself as a rather skinny person and I wanted to know if I needed to bulk to get more mass.
I don't mind if I have to, but I can't always pick what I want to eat everyday. Even if it is essential, I still can't pick for myself.
I usually do push ups. About 10 slow reps. I do about 3 - 5 sets of these.
I also sometimes do squats and calve raises ( without equipment ).
I have quite a bit of time in my hands and would like to focus on the above parts in strength and mass.
The only time I don't have time is when I have assignments and studying for exams.
I also don't want to be massive like a bodybuilder.
Just want to increase mass and strength and maybe endurance.
Thanks!

 

[StefanH]

Get a set of dumbells, their cheap and easy to find, then look up a few dumbell excercises on the internet. Its a great way to get a toned body instead of a completely ripped look, just dont overdo the weight because your still young and you can damage your joints by working out with too much weight.

 

[qadar]

Do the right exercise. Take on a free course. Here is one which helped me.

http://www.easyabsworkouts.com/