As above, fronts are dictated by the holes in the door aperture which house the pin on the clamps of the front bar. Rears, on a 3-door, are dictated by the marking on the glass of the rear quarter - if you look at the 'dotted' part of the glass at the top there will be two little arrow marks, just site the foot and clamp in line with these. The clamp slides in above the top of the glass. Can be a bit daunting the first time you use them as the shell can creak as you tighten but as long as you only tighten using the supplied torque key (twist until the two arrows on the plastic body align) then you should be fine.
Hope this helps.
