Chart-topping rapper Soulja Boy Tell'Em explained Wednesday at Billboard's Digital Music Live event, which is affiliated with the Consumer Electronics Show, how the Internet helped launch and sustain his successful career. The Grammy-nominated musician's song "Crank That" became a MySpace sensation and an instructional dance video to accompany the track was a hit on YouTube. Pictured: Michael Crooms (a.k.a. Mr. Collipark), Soulja Boy and Billboard's Bill Werde