Hi Peter,
Having installed the Lame MP3 Encoder on your PC, you need to inform Audacity where the Encoder is located on your hard drive and then the program should find the Encoder automatically.
If you are still experiencing problems, try downloading the latest version which is available here :
http://www.mp3-tech.org/software/encoders/lamewin32.exe When you access this link, just choose to 'Run' the application. If you receive a security warning, just click on 'Run' and the downloading process will start. Agree to the software license and on the next screen, untick all options except 'Lame 3.94' and click on 'Next'. Accept the default location for the installation (C:\Program Files\Lame) and click on 'Install' - the installation will proceed. Close the window when completed.
Now when you wish to save an MP3 file through Audacity, the first time you choose the option to save as an MP3, Audacity will attempt to find the Lame encoder files. If it cannot find the files, a message will appear on the screen, advising you of this fact and asking if you would like to locate the Lame Encoder.
Click on 'Yes' and when the
'Where is Lame_enc.dll' window opens, navigate to the 'C:\Program Files\Lame' folder, where you should see the 'lame_enc.dll' file - now click on 'Open'. Audacity will then note the location of the Lame Encoder. You only need to do this once and during future MP3 save operations, the program will automatically find the Encoder.