To adjust recording level of mics and audio level of produced videos:
Audacity (Free - but I suggest a $25 donation) It's a GREAT program.

To record tutorials: 
Camstudio Recorder (Free)
http://camstudio.org/   This program records your computer screen, with your narration.  If you just want to combine videos from sources like cameras, and don't make video tutorials, you probably don't need to use Camstudio.
Debut Video Capture Software ($40) from NCH software. Does the same thing as camstudio, but works better with more than one monitor, and will record from both mic and computer sound simultaneously. After using both Debut and Camstudio, I prefer Debut.

Cyberlink Screen Recorder (included with PowerDirector)  Generally the best and easiest way to record your screen, as is well-integrated with PowerDirector.

To edit video tutorials:
Cyberlink Power Director 13 Ultra ($80)
http://www.cyberlink.com/ This program is VERY useful. With it, you can edit video tutorials, or edit videos from a camera or other source.  And you can record or change narrations for your videos.

To store videos on Youtube (free)
http://www.youtube.com/   Free way to share your videos with friends (and the world, if you so choose).

Note: Gaming headsets (mic + headphones) are available for $20 and up).  Be sure to get one with the right connectors, and be very careful with the headphone cable.  It is very EASY to catch it with your foot and pull the wire out of the plug.  It is very difficult to fix!! I recommend using a high-quality separate microphone for recording videos for posting to YouTube. See the video below: "How To Install And Adjust Mics...".

For complete instructions for making your own tutorials, including how to use CamStudio, Debut, Cyberlink Screen Recorder and Cyberlink PowerDirector, see Youtube Playlist :  How To Record Video Tutorials

This playlisit has these videos:
Intro
Update Your Video Card Driver:Update drivers from video card website to prevent problems.

How To Use Audacity To Adjust The Audio Volume Of Home Videos.

How To Ue Audacity To Adjust The Recording Level For Mics With Preamps.
How To Install And Adjust Mics For Windows Computers:Connect various types of mics to your computer.
Record Computer Screen With Debut:Use Debut Video Capture Software to record desktop & narration.
Record Videos With Camstudio:Use Camstudio Video Recorder to record desktop, provide narration..
Record Videos With Screen Recorder.
How To Record Your Ipad Screen With Reflector 3.
(All remaining videos use Cyberlink PowerDirector Video Editor.)
Basic Video Editing Part A:Edit combined audio/video.
How To Select And Use Microphones To Edit Videos.
Edit Audio:Edit audio portion of video.
Convert Mono To Stereo:Add missing audio channel (necessary only if you record with a mono mic).
Additional Editing Functions:Rotate, crop, brighten, etc.
Basic Video Editing Part B:Edit combined audio/video.
How To Make A Simple Video Title:Make simple title with Wordpad or MS Word.
Insert Photos With Narration:Insert photo within video, provide narration.
Best Method For Narrating A Photo.How to use Debut to narrate a photo BEFORE inserting it into the final video with PowerDirector.
Censor A Photo.  How to obscure part of a photo to protect privacy.

To upload your Videos Tutorials (or any other videos), see Youtube playlist: How To Create A YouTube Channel .