If you know basic construction it is easy to do. If you remove the trim from your bathroom vent you will see how they use dimensional lumber to box between the trusses. You will need to have a stud finder to locate trusses... mark the size and location on the inside ceiling and cut the opening there first. Then create the "box" as was done for the vent. Drill a hole at all 4 corners thru the roof....then from the outside cut the roof membrane in an "X" forming 4 triangles to be folded back...CAUTION at this point do NOT remove any membrane. Mark cut lines on the plywood from hole to hole forming the box and cut and remove. Fold the membrane into the opening and staple down and trim excess. Now follow the instructions included with the skylight to complete the install. Be sure to buy a skylight that works with the curve of your particular rig as some are NOT going to conform to a high center point curved roof.