Also where is the best place to line up the runway in the front screen and how much should you allow the aircraft to fly it self as it were?
The object is to keep the aiming point, the place where you want to land, in the same place in the window, where that is will depend upon your height and the aircraft's altitude and distance from the runway. By doing this the aircraft will fly a line of constant bearing to the runway. Trim the aircraft and let it fly itself, it will do the job better than you ever will.
My approach seems to be fine but when about 500ft agl I seem to start over controlling
In a normal circuit you will not be on the centreline till 500ft, so how can you be flying an approach before that point?
Get your instructor to demonstrate, that's what he is there for.