Aura over my target

[Just me]

Hi, i know this will seem very dumb to most of you, but figured no harm in asking. Ive got 3 80's, 2 Healers and 1 ranged, and now i thought id try a melee toon. On a single target obviously im fine, but when a mob or say in pvp when there are multiple ppl at me i cant tell who im targeted and half the time find myself spammed with 'Your facing the wrong way'. Ive been told your first melee toon is usually a disaster, and all takes time, but was wondering if theres an addon to put an aura or mark on my target or who is attacking me, so i easily see them amongst groups. I was told power auras did it, but cldnt get it to work for me and just kept the buff on me instead of buffing my target/attacker. Thank you muchly for any advice, ive been driving myself nuts..