How to customize your iphone homescreen?

I want to edit my apps icons, is there an app to do this? I've seen other people do it but i don't know how to do it? Any help?

This is only possible if your device is jailbroken. Learn how to jailbreak your iPhone at http://iosuniverse.com/jailbreak

Select your device and firmware, and it'll tell you what tool to use if there's a jailbreak available. I use it all the time!

That involves jailbreaking.