[billneilson]

When I attempt to open a puzzle, I am asked it I want to go on the web to find a program to open the file with .puz extension.

[Doorbell]

I can think of two things:

1) .puz files require the Across Lite software.  If you don't have it on your computer, you can download it here: http://www.litsoft.com/across/alite/download.htm

2) If you've already installed Across Lite, then you need to make a file association between the .puz extension and the software.  To do this -- on Windows-- go to the Windows Help and Support feature, search for file extension, and follow the instructions (which are pretty clear).  I don't know how this is done on a Mac.