Runescape Camera Rotation?

Before starting, I ALREADY KNOW this has been asked several times before me, but I just couldn't find what I was looking for on those Topics. Ok, so basically I'm developing a medieval game, and I want the player able to move around like runescape (Click to move), and I've achieved that goal, as well the camera follow and a zoom. BUT, I need a script to have on my camera, to be able to rotate it around the player, using the arrow keys, right and left, and maybe vertically and horizontally.

Since I'm REALLY new into Unity 3D my coding knowledge is NONE. To reference the camera Rotation I'm looking for, it's the same used on the very famous MMORPG called RUNESCAPE. PLEASEEE HELP ME :(

EDIT PS: My Unity knowledge it's pretty low, so I would like to have a very simple answer, terms I can understand, thanks a lot