apple2005, you need to start playing around with some audio and video editors.
if you want to go fancy, you can use something like sony vegas, but that costs money.
or there are various free tools available, however these are pretty complicated and daunting to a beginner, but you do have to start somewhere.
one useful video tool that i like and use from time to time is avidemux
- it's pretty simple and straightforward, and is able to make your video files sound louder, by adding gain to the audio track, and it can turn a mono sound track into fake stereo. a very quick and dirty avidemux tutorial:
open your file
in the audio section on left-hand side, click where it says copy, and change it to aac.
click configure and chose a higher bit rate than the default, so you don't lose too much quality.
now the important part, click filters: in the mixer dropdown, you can chose stereo, and in gain mode, you can chose automatic - this will boost your audio.
finally, save your video, using the original format, ie if it was called foo.avi, save it as foo2.avi. avidemux seems to forget to add the .avi (or .mkv etc) file extension on, so make sure you add it when you save. don't mess with the video section, or else you will be in for a long save as the software has to reencode all the video, which is a far tougher job than just boosting the audio.
hope this helps, and good luck!