Takes about half a day to do, you will need some screws or rivets, maybe some kind of bonding/glue and G-clamps, and a set of arches and skirts sprayed to match your car.
Basically you need to remove the front arch spats and mudguards if you have them, then glue on and screw on the arch pieces, then glue on and screw on the skirt pieces. Use clamps to hold them in place while the glue dries. There are guides on how to paint and fit them on the FAQ/Guides section of this site and on .
I've heard its a bit trickier to get them on a 5 door but I had no problems doing mine on a 3 door. Although did it over two days where it was p*ssing with rain so was laying under the car screwing the skirts on in about an inch of water
