First you need a S3 launcher . So Click on the download button below and extract the downloaded files , it contains theme.
This theme will not open on their own, you must install the application home screen free "EX GO Launcher" and apply it.
HOW TO INSTALL
1 - Install GO Launcher
2 - Apply the Theme: MENU-> Themes-> Choose SGS3 theme.
3 - Then install the Galaxy S3 Dandelion LWP
4 - Go to the Launcher menu and click Go: Wallpaper> Wallpaper Animated > Select Dandelion Galaxy S3 LWP.
5 - Okay, now you have a custom launcher Galaxy S3
Download S3 Music Player from here
Add auto lock feature like S3 using this guide