This type of vinyl is very easy to use....like Minzguy said it's forgiving if you mess up it can be reused with enough patience.
just cut the sheet to about 1 inche wider then the trim then using the heat gun or hair dry to head it up then bend / fold the edges .If you get an air bubbles just seemly heat it up and pill the vinyl up the work your way around the vinyl then push the pubbles out.