Just follow these directions:
1. Download the Sprint theme to your phone (
http://ilkevinli.zftp.com/Phone/Sprint_Theme.theme )
2. Open Diamond TF3D Config and click on the Appearance tab
3. Click on "Path" and select the folder that contains "Sprint Theme"
4. Click on the drop down box (below Path) and select "Sprint Theme"
5. Hit Apply
Thats it.