At the moment I’m using Windows 7, and I’m using 2.1.1 with the .exe installer.
I’m using LAME to turn my file into an MP3, and after I save the file it turns in to a normal file or a NET) file. My LAME is v3.99.3 and I don’t know what to do. 
See [u]this page[/u].
After you’ve downloaded this file: “Lame v3.99.3 for Windows.exe”, make sure you run that file to install LAME. Then when you want to make an MP3, go to File → Export (export, don’t “save’”).
Or if all else fails, export to WAV and use a 3rd party program to make the MP3. [u]TAudioconverter[/u] can convert between several different formats.
If Audacity recognises LAME, are you putting dots (periods) into the file name? If you do that, add
.mp3
at the end of the file name before you export.
See Audacity Manual.
Gale