How to customize your Xbox 360 gamer picture?

I want to customize my xbox 360 gamer picture like soulja boy, soulja boy has the 2 lines on his eye lashes and also on his gamer picture...how did he do that..or how can i do thatHow to customize your Xbox 360 gamer picture?you cant do that.are u talking about the avatar??if so just go to customize avatar and do it