How can I add fade in and fade out effects to a video?
Windows Live Movie Maker is a free app that can do both audio and video fades (both in and out).  You probably already have this application installed on your computer, and if you need further help I would imagine you can find a number of YouTube tutorial videos.

Once you import your video, click on the Edit tab and you'll see the audio fades immediately.

Then, click on the Visual Effects tab, and click the down arrow at the right of the single row of effects to expand these.  Scroll down to "Motion and Fades".  In this group you'll find what you're looking for.

If you don't already have WLMM on your computer, there are a jillion places where you can download it.  Incidentally, the latest version is called "Windows Movie Maker 2012", for Windows 7 and 8, so you'll want to look for that unless you're still running Vista or XP.