Transfer the finished master (stereo) mix to your computer via USB. If you don't have a computer, or need to have someone do it for you, burn the final mix to a CD, bring the CD to the friend's computer to do it.
I believe your Myspace tune will need to be in MP3 format to upload - any music software (Roxio, Nero, Audacity, etc) will convert from WAV to MP3 format (maybe the DP-02 will save it in this format, too). If you don't have software to do the conversion, check out download.com.
Once you have the song in MP3 version, go to your myspace site, click on "Edit Profile", then click on the 'manage featured songs' tab, and follow instructions to upload your song.