What is the installer app on iphone 4?

I want to change the color of the texts i receive and send but one of the first things is to go to the installer app, how can i download that app or how do i get it here is a link to the info i got from the steps
http://www.ehow.com/...bbles.html

It's an app you get out of cydia (jailbreak). You shouldn't jailbreak your phone.