I NEED Some Urgent ADVICE QUICK!!!?

Im doing some lowlights for my mum and I need an easy step by step guide on how to do it. I think I have a ruff idea on how to do it. Ive cut out some silver foil (Ruffly 3 inchs on the top and 6 on he sides) and she wants it all through her layers and wants it to look natural. She chosen Loreal Paris Casting Creme Gloss 415 Iced Chocolate. Im doing it tommorow and I need quick, easy and serious advice. PLEASE HELP!!!