If you have created a .wav file you might want to save it as an MP3 for download and distributing. This can be done using software called Audacity.
The link to the Audacity application is:
Because the MP3 algorithm is copyright, they cannot include export to MP3 capabilities directly into the software. If you choose the Export to MP3 option you will be asked for a .dll file, which is available in LAME: