Creator (interface builder) can not find the interface! ! !

iphone beginner novice, I can not find the interface builder.
Xcode version is 4.0
May I ask how out of tune interface builder? ?
Reply:
Xcode version is 4.0, interface builder has been integrated into Xcode, and simply double-click on it to open the UI design xib
Reply:
Thank you!
Reply:
I want to know! Thank you