Tosh it comes with instructions and a special spray with a plastic squeegey, make sure the paintwork is clean, measure up (i used masking tape and a pencil), measure again, then spray and apply. its very satisfying and once youve got the first sticker on you will be sorted and youll be a pro by the time its finished!
Use more than one colour as the price is the same and it stands out well, i went for red and blue and it stands out well on a white van.
Good luck and put some pics up when its done!