Fitness exercises, giving a personal advantage?

[DreamerOfSport]

I want to gain more muscles in my arms, upper body and lower body by using dumb bells, so that this will help me in any physical activity i do. Im only 15 but i want to be better at my sports so what are some exercises that will help we increase my muscle sizes. What are some other activites/exercises that help my core strength and help me increase muscle sizes without using a dumbell? What are some activites that will help me sustain my fitness and stamina during summer. Im pretty skinny so what foods or meals can i eat to help me get more fat, to make me more solider. At start i wont be doing any heavy weights but any sort of muscle growth will please me.

Any tips or sites will be a guarenteed help to me, So cheers!

Thank You.