Why do I have to do to jailbreak an iPhone 4 with encasi0n 7?

I tried to jailbreak my phone with Envasi0n 7 but after all the procedures the app doesn't turn into Cydia like it's supposed to. What are the procedures?

Don't jailbreak with Envasi0n 7

use evasi0n7 http://evasi0n.com/
evasi0n7 is free and its the best and easy jailbreak for ios7 and works very good without any problems