How to convert .wav's(.wav) to .mp3(.mp3)??

I recorded a bunch of funny songs raps using my laptop and the mic thats installed in it that it comes with manually , to veiw the songs i record theyre found in my pictures, I just double click them they have like a musical note on them and then windows media player pops up and that track i clicked on begins to play, l'd like to know either how to put these on my ipod , or how to convet them into mp3's so l can put them on my ipod, thanks!!!!!!!!!!