do you just want to convert the wav into an mp3? or do you mean something else because if you just want to convert the wav into an mp3 you can use this its free!
just drag the file you want into it than go to the top right hand corner click the 3 dots and choose which file you want it to go into than just go to video tab in the bottom left corner and uncheck the box that says enable video and than go to the audio tab and choose which format you want.