Foil adhesive is applied in the area on the nail that you want the foil to be. It is allowed to go clear (normally they start out with a blue tinge). In the meantime cut off a bit of foil the size you need. You then apply it over the glued area and press hard and it leaves it on the nail. Nail wrap finishing sealer is applied to seal it in - not difficult at all. Hope that made sense.
its so easy, some adhesives have a cloudy appearance to them but like carole said they go clear and sticky, the you place the foil over it rip it off and walla!!! u have a pattern on the nail. seal it with sealer. they are fab when you want nail art quick and easy.
Like the Carole and Snuggles have said already, but you need pattern side facing you when you apply, and really rub with with cotton wool or a nail wip to get the foil to adhere well to the nail....hth
Just a note on the sealer, I love foils but every sealer I had didn't do the job, so I've started to use the Brisa UV Gel to seal it. It lasts so much longer, the only thing is you have to buff it off to change your nails.