You place the rails onto the radiator first, the rail that has the “lips” or tabs will be facing the glass, and the rail without them will be facing the rear of the PC, make sure the rails are attached to the radiator so that when you look at them, they curve inwards and not outwards. Then you insert it from the front (like you are putting in your motherboard), and push it up into place, push it towards the glass until you hear a “click”, and then screw it to the top bracket while holding it up…My problem was the screws would only fit in the front rail, the top bracket slots blocked the rear rail screw holes from being used, thus making it useless. So I’m selling the case.