Ringtone problem

[mrsmdh]

I've downloaded some ringtones from phonezoo.com and myxer.com and they save to my phone (Sprint Touch Pro running Fallen Rom) as files with .gcd extensions. But I can't open them. I get an error message when I try to open them that says there is no application associated with the file, run the application first then open the file.

But I don't know what application to use to open it. I've tried Windows Media player and Core Player with no luck.

Any suggestions?