glGo requires Mac OS X 10.3 "Panther". It does not run on OS X 10.2 and earlier.
To install glGo, mount the disk image you downloaded in Finder and copy the glGo icon to your Applications folder. If you also want the Playermanager, copy the Playermanager icon to your Applications folder as well. The Playermanager is optional and not required to run glGo. That's it!
To uninstall glGo move the glGo and Playermanager icons from the
Applications folder into the Trash. You can manually delete the directory
/Users/yourname/.glGo to delete the glGo
If you want to play with GNU Go, you can download a ready-to-run GNU Go for Macintosh from the glGo webpage.