To save your tracks as MP3s, you need the LAME MP3 Encoder, which is available under 'Optional Downloads' at the same site. STEP 1. Opening Tracks Once you start ...

You'll also need the Lame MP3 encoder - this add-on is necessary because Audacity can read but not write MP3s. You'll find a link for downloading the Lame MP3 encoder on the Audacity site.