Preamble: KML support in the Minimap sidebar is best described as experimental. I have not fully tested to the full and there may be issues. There are a few known issues with kml:

• You cannot drag and drop a local file; use import kml for this.
• When dragging and dropping a link, the addon cannot recognise if it is a kml file, it tries to guess. It will look for files ending in .kml or .kmz, it will look for links with =kml or =kmz in, anything from Google MyMaps and anything from keyhole. The workaround for files not recognised is to manually add the url using the toolbar add kml dialog.
• You cannot import kmz files, and importing kml files will only bring in placemarks.

Viewing

To view a kml file, drag and drop the link onto the Minimap Sidebar (alternatively right click link and select open link in sidebar). This uses the Google Maps API ggeoxml function to display the contents.
http://kml.lover.googlepages.com/my-vacation-photos.kml

Another way to view kml files is to copy the url and add manually using the add kml toolbar dialog.

Once a kml file has been added, it will be stored in the kml/georss tab, where you can toggle visibility, edit the title, and delete.

Importing

If you would like to import kml file placemarks into your address list, save the file to your computer, open up the Minimap sidebar, go to the ‘tools’ menu button on the toolbar and select ‘Import -> kml’

Exporting All address list items

If you would like to export all of your address list items as a kml file, open up the minimap sidebar, go to the ‘tools’ menu button on the toolbar and select ‘Export All To -> kml’

Exporting a selection of address list items

If you would like to export a selection of items from your address list, use ctrl+click (mac cmd+click) or shift+click to get your multiple selection, then right click and select ‘Share Location -> Export as kml’