Click the download icon to start downloading the SMUG iCal calendar file.
You will then select [ Open in "Calendar" ]
You will be presented with list of events, click on any event and then click on the "Add to Calendar" button
You can then select which existing calendar you wish to add these new event to, or just add them to a "new calendar" and name it "SMUG" or any name that you'd like.
You can then goto iCal and check to see if the newly added events appear in calendar option you selected.