How do i change a song to an mp3 format?

I'm making a powerpoint and I need a song that was downloaded from the internet on to it and when I try it says that I need to enter a path that points to a location on the computer and that I cant use an internet address here.How do i change a song to an mp3 format?
first of all, if ur gonna upload the song to the powerpoint presentation u have to convert it into *.wave not *.mp3 , and however to convert any extention u can use the moviemaker, and if it doznt work with u , use a mp3 converter by downloading any one form the internet.

http://www.audconv.com/

http://www.smartaudioconverter.com/

http://tunebite.com/en/remove_drm/index.How do i change a song to an mp3 format?
Download the song then.



Get the link, right click on it and select ';Save Link As...';. Then just use it from your computer and everything should be fine!
Depending on the original format look here for software.