How do I import a CAD file into Google Earth?

Importing Google Earth Data
The data you will import into AutoCAD is exactly what is shown in the Google Earth window. Next, open an AutoCAD drawing and make sure you set any map zones or coordinate systems you want to use. Now, just go to the Insert tab on your ribbon bar and click on the Google Earth

TRICKS

Step : 1   How do I convert DWG to DXF?

Conversion from DWG to DXF takes just five simple steps:
Open your DWG file. To do this, select File Menu > Vector > Load. Select DWG in the File Type dropdown menu, select the file and click Open.
Click File menu > Save As.
In the File type box, select DXF Format.
Select a folder and enter a file name.
Click Save.

Step : 2   Download QGIS 

DOWNLOAD LINK

Step : 3  What is KML in Google Maps?
KML (Keyhole Markup Language) is an XML based file format used to display geographic data in an Earth browser such as Google Earth, Google Maps, and Google Maps for mobile. With KML, you can display pretty much everything on a map.