So the recording is a mix of your voice and the other peoples voices all on the same track?
If so, there's not a great deal that you can do about it, but you may find that "Chris's Dynamic Compressor" helps to even out the levels.
http://pdf23ds.net/software/dynamic-compressor/When you find the link, RIGHT click on it and "Save As". (left click will just display it as text in your browser).
The file should be saved as "compress.ny" and placed in your Audacity plug-ins folder. It will appear as "Compress Dynamics" in the Effects menu when you restart Audacity.
A suggested starting point for settings is to set the "compress-ratio" to 0.7 and leave everything else at defaults.