CO2 is telling yo to start over again.
If you don't understand, or it it still does not work, go to the site and read carefully. Follow the instructions as given.
Install only audacity. Get the LAME encoder.
Do what they tell you on the web site.
Audacity will install the encoder into itself.
http://audacity.sourceforge.net/EDIT: If you do not get it to wokr, come back here.
There are people here who are ready to help and have the right answers