If you are trying to get the sound into a mission:
Get the sound file, convert it to .ogg format using a codec (
www.vorbis.com) and use OFP Cool Studio (
www.ofp.gamezone.cz - Utilities section) to create a description.ext.
In your folder of the mission you want to put the sound in, create a folder called "Sounds" and put the .ogg file into that.
Check out various tutes on this site for more info.
Hope that helps, if that was what you were trying to do.
If it doesn't work the 1st time try and try again. I just recently got my first bunch of sounds into flashpoint. (the red hot chili peppers' album)