they have what you call application fluid to spray on before you apply but i use soapy water, this allows you to move the decal around a bit to make sure it is right, then squeegie out the bubbles with a squeegie (or your wet fingers)

the link below sells anything you need, also will make you some pretty neet decals

here is a pic of a decal they made for my granddaughters plane i built.

http://www.speedysigns.com/accessories/