For simplicity, you can do the following the achieve same result as OP.
1. download Arcsoft 5 0 94 128c at
http://forum.ppcgeeks.com/attachment...4&d=1256947252
2. Unzip attached SprintMMS.zip (Note: If you don't have RegEditor, use attached TaskMrg, it has regeditor inside to import)
3. Use TaskMrg below or your RegEditor to Import registry files to your phone
Go to Start --> Email -> SMS / MMS --> New --> Picture Message and compose ur MMS
Enjoy!