I put together a video tutorial that plays in Windows Media Player showing how to make a basic custom map for your consumer grade Garmin GPS.  It shows how to make a map from GPS tracks that installs into Mapsource where you can then upload that map to your GPSr.  There is a READ_ME_FIRST.txt file included with step by step instructions to follow along with the video.  This tutorial is a basic example of custom map making...you can make more complex custom maps of roads, rivers, water bodies, towns, topo lines etc by including data available from various GIS sites.

Download tutorial here:

http://www.mediafire.com/?94ks0g0xj3t