For First you have to Buy the Iphone Glowing Backcover the Set includes a Iphone 4/4S Backcover with a Clear Apple Logo, Fixing Tools, LED Panel, Stickers for style change.!
Here you can see the Video Instruction would be more Use & Helpful for you as a Step by Step Instruction Only with Text .. Watch it and you will replace your Backcover within 40 Minutes as Beginner ..
So here we going Step By step.:
Step 1.: Close your Phone
Step 2.: Remove your Backcover with the 2 Screws on the Bottom of your Phone
Step 3.: Remove the Battery Connector with 1 Screw
Step 4:: Remove the connector Shield with 5 Screws
Step 5.: Pop up the 2 small connectors (seen from right side)
Step 6.: Cut a small slice of the include. sticker and add it exactly in the middle of the 2 connectors ground (To Protect the grounded connector pins)
Step 7.: Add the RED cable of the small LED Panel exactly in the middle of the 2 connectors and let it touch at the bottom of small e-component as seen here ..
Step 9.: Pop back the Connectors, Fix the LED Panel on a place match the Apple logo of backcover later, add a small pcs of glue tape to battery and paste the Panel on it. !