Its so easy im a 13 yr old too and i already built my own pc even my father was amazed at how much strong it is how aggressive it looks and how much i saved.. you could use my build
NZXT (Guardian 921 RB) Steel Midtower Chasis Black
Intel Core i5 2500K Unlocked 3.3GHz (Quad Core), Freebies
Razer Kabuto Gaming Mousepad
500gb WDC Caviar Blue (WD5000AAKX) 16mb sata3 hdd
A4tech (KD 800L) lighting keyboard
lga1155 Asrock Z68M USB3
Samsung 20" (S20A300B) LCD, LED
Cooler Master Silent Pro M 600watts
G.Skill RipJaws X (dual) 2x4gb ddr3 1600 CL9
Gainward GTX 560 Ti Phantom 2 2gb/256bit ddr5
Roccat (Pyra) Wireless Gaming Mouse