if you have an inkjet printer,go to Wal Mart and get thier kit(it has some white paper,clear,and bonder)
thier program isn't very good,but if you have Paintshop Pro,or another good photo program use that...create the decal that you want and print it on REGULAR paper first to confirm the size is correct
after your satisfied with the result,use the decal paper(if it has ANY white in it,use the white paper...let it dry for about 10 minutes and then spray a light coat of bonder on it,,let that dry for about 20 minutes.
cut the decal as close to the edges as possible and it's ready,,,they seem to be a little fragile,but work well