im an asian guy who wants dreads so i can tie em back and have them stick up to get a samurai type look

how long does my hair have to get and do i have to get a perm?

No, you don't need a perm. You'll just need longer hair, a lot of dread wax (like from KnottyBoy), and a lot of backcombing and twisting. If your hair is a typical Asian hairtype (bone-straight, slick, coarse), then you'll want to put small braids in your damp hair the night before. That way it will give your hair some texture before you start dreading.

How long is that samurai look? Count on between 30-50% shrinkage when you dread your hair, so you'll want to grow your hair longer than you want the dreads to be.

Here's some extensive http://www.hairboutique.com/tips/tip285.htm - information about dreadlocks  on Hairboutique
And here's a step-by-step http://www.knottyboy.com/learn/stepbystep.php - How-to for Dreads

Hope this helps
Anais