When you share your calendar with others you have the option of allowing visitors to add your events to their calendars. Your visitors will be able to add events that they save from your calendar to any other calendar that accepts .ICS files (ex. Keep&Share, Outlook, Google, etc.).
In order to turn this feature on for your events, you'll first need to create an event. In the event editor, you'll need to add a link to your event. When your visitors click on this link it will automatically download your event to their computer and they can then import that event into the calendar of their choice. Follow the steps in the image below:
After you've clicked on the "Attach Links" tab a link dialog will pop up. You can choose the text you want to want to have in the "Link Text" field, but you'll need to choose the "Download .ICS" file option from the drop-down menu. Follow the steps in the image below:
After you've saved your event, it will look like the event below. Visitors only need to click on your event link and the event will be downloaded to their computer. You can only set the "Download .ICS" option per individual event. There is not a way that you can automatically have this feature turned on for all events you add to your calendar.