i figured out how to do it
i'am really happy about it
its not that hard to do
here is how i did it
1. find a theme you think is the best for SHIII
2. copy the link from the url bar
3. go to
http://mediaconverter.org/
4. insert the link (or upload a music file, uploading works better)
5. click go to next step and select the sound file you want in this case .OGG
6. download the file, now you change the name to: Menu_Master LOOP
7. go to you SHIII/ Data / sound/ music and search for the Menu_Master LOOP file and take it out of the sound file and make a back-up
8. drop you Menu_Master LOOP file into the sound file, close all and start SHIII, if you did everything right then your theme should be played
greets
Liam