Visual Glitch

so i just started playing LOL and now im trying to play against bots. to get started. but my whole screen goes insane and it looks like its glitching out. like old tv's. idk how to explain it. i just see bars of the game going up and down. and no its not my screen. i played other games on my laptop without problem this is like the worst way to start when you want to get into a game...