Loft ladders generally come in two versions: either aluminum or wooden. However, although personal preference will dictate which one will be right for you and the situation you are in, they are both fitted and attached the exact same way. As a result, you can use these directions to fit any type of loft ladder to nearly any loft.
Set up your ladder so that you can attach the brackets. With every loft ladder will come a pair of brackets to fit. Put your ladder underneath the actual loft and climb up to the level of the attachment point.