Be sure you use the latest version of GPS Utility. To import the .html file you have to select 'MapsOnUS (html, htm)' in the file format list of the 'File->Open...' dialog. I don't know why the author didn't make an extra menu entry for greenflag.com; maybe he just forgot it. I think you also have to select step by step instructions, because the coordinates are used as an argument for a script or something to draw the mini maps.

Thorsten