Uh ok. Well you open the program (make sure to patch it first and READ THE INSTRUCTIONS INSIDE THE ZIP FILE).
1) Enable mp3
2) Choose "Mp3 through wav file. Keep wav"
3) Go to Create mp3 and search for it. Press ok and you're done.
The mp3 will have the same exact name the wav file has and it ll prolly be located in the same folder. If you have any problems just tell me.
http://www.megaupload.com/?d=4J6JDS70