I am looking 4 a hairstyle that is 2-toned in back... a darker color underneath?!? pics would be great:) t/u?

poss called a 'Rock Star' hairstyle, but i'm not sure. I'm getting my hair done tom and would love a pic 2 show the beautician; also... any idea's on what color to do underneath... i have a med brwn natural?!?