The whole shrink to fit business can be a bit confusing, so Levis Vintage Clothing made three instructional videos to help you through the process. Of course, you can also ask us!
https://www.youtube.com/watch?v=auzDQIfnZ2A&list=PLv2owRmD8gH8qloAvzA-tPgnSD5KioaJ6&index=3