To find then you need Astro file manager (free) from the market This will allow you to browse your SD card. To make them show up as a ringtone you can do one of two things:
Plug your phone into your computer, set it to disk drive then under the folder called DCIM either create a folder called ringtone or put the sounds into it.
Your other option is to get Rongdroid (free) from the market. When inside, brows to find the sound then hit edit then save it as a ringtone.
Sent from my HTC Thunderbolt 4G using Tapatalk.
I cant seem to get the first idea working for some reason.
Also, I cant find Rongdroid....are you sure that is the right program?