How can you convert files to mp3 format?

You need to have any special audio files converting software to convert audio files to mp3 format... For example I use a famous software called AUDACITY to convert WAV format files to mp3 format.... You can download the latest version at audacity.sourceforge.net for free... Open the file through Audacity and go to File ---> Export... option..... Give the appropriate details if you want and save it...
Your job is done!! :)

Or else, you might have the older version of Audacity which would say it requires some kind of a dll file to convert a file to mp3 format. That file is known as lame_enc.dll. The instructions to download that file is at http://audacity.sourceforge.net/help/faq?s=install&item=lame-mp3....
This enables you to convert files to mp3 format with older version of Audacity...

After downloading, locate the downloaded file when you want to convert...