.wav file to be converted to mp3

I have recently installed Audacity version 2.0.3 on my computer with windows 8.1 os. I recorded a cassette tape and the file created was in .wav format, which I copied on a usb drive and tried playing on an MP3 player. It did not replay. How do I convert the .wav to mp3 format? Thanks Arun

That version is over 4 years old. The current version is 2.1.3 and is available here: Audacity ® | Downloads

To export as MP3, you need to install LAME. Instructions are here: Installing and updating Audacity on Windows - Audacity Manual

Hi. It’s suggested that you upgrade to the latest release of Audacity (2.1.3), which can be found here:
http://www.audacityteam.org/download/

You can convert the WAV recording to an MP3 by installing the LAME encoder, which can be found here (look for this: RECOMMENDED Installer Package for Windows: Lame_v3.99.3_for_Windows.exe):
http://lame.buanzo.org/

Alternatively, if the file isn’t too large you could upload it to any of those “WAV to MP3” online conversion services and it’ll convert it for you automatically.

Thank you for the prompt response.