Veigar build?

so basically im a new lol player i am rank 23 and bought veigar cuz the other veigar was doing insanely well with him. I get his abilities but was just wondering what builds i should go with him. I mean i have soooo much to learn. At the begging of each math i dont even buy anything and just save up for rodge of the ages(same thing for any mage class hero i play). So i want to know what EARLY game items i should buy that FEEDS into the good late game items that are suitable for veigar. And i watched some videos and veigar gets AP (what is AP btw? and the other terms you pros use?) when he last hits with his q ability? anyways i have so much to learn. I just want to know a decent build for veigar that will get me op like that one time when i played master yi and got 31 kills (just went a bunch of dmg. imo btw storm razor op). thanks for your time!