Ev training Pokemon White?

Ok So I want to Ev train my Riolu Lvl 50 and its nature is Hasty and I'm planning on making the attack and speed high. Can someone give me a fully detailed explanation on how to ev train? My friend said to attack a basculin like something times so I don't remember lol. Please teach me how many times and all it takes to battle the same pokemon and the rest of EV Training PLZ !!! Thx ((: