Publish to KML
Publishing to a KML file is done by making a Plan Presentation, and then picking that as the plan to publish to KML.
Make a Plan Presentation
Include the data you would like to publish
Choose a Presentation Setup that shows your data
Finish the Plan Presentation and see that the content looks OK.
Make the KML file based on the Plan Presentation
Go to Output > Publish
Choose the KML format
Pick your Plan Presentation to publish
Finish the Publish and check that the content looks OK in a viewer
You can check the file in f.ex. Google Earth or another KML viewer of your liking.
Next topic: Publish to PDF 3D