How to make volume increase for end of videos?

I’m generating instructional videos and want to have a background soundtrack which get quieter for the body of the video, but is at a louder volume during the intro and outro.

i understand how to have the volume fade down to make the music during the introduction get quieter when the actual video begins but can’t figure out how have it fade UP and get louder so for the outro it will be back to the original volume.

The Envelope tool: http://manual.audacityteam.org/o/man/envelope_tool.html is the official tool for the job.

There’s a new “Adjustable Fade” plug-in on the way which can fade up as well as down.
If you find the Envelope Tool too fiddly please say so and I can send you a link to the pre-release version of the Adjustable Fade plug-in.