to build muscle you obviously need to work out and get alot of protein!

you should aim for 1-2grams of protein per lb of bodyweight.
eat plenty but split it up into like 6 meals a day so your body is constantly fuelled.

eat things like ( chicken, tuna, steak, vegetables, fruit) you have to no which is high carbs and low etc. your best for protein is the chicken and tuna though.

if your wanting to put muscle size on then your gonna have to bulk up that means eat more than average you will put on fat aswell but if you do it correctly not much.

cardio- 3 times a week for about 30 mins each time (running)

then once youve got to the point your happy say like after 3 months bulking then you cut which you would take out most fat foods and high carbs. do more cardio then yull end up with a more lean look but you will lose sum muscle size and thats where its most important to have alot of protein to keep muscle mass.

*GET A GOOD ROUTINE with the weights for mass small reps lift heavy. if you need a good routine il post up a good mass building one if you aint got one already.

if you need any more help then just ask me some questions il try my best.

check out muscletalk.co.uk they cover all things.