Double-click the Google Earth installer, or right-click and choose open. Some browsers may open a window asking if you want to run the program that you just downloaded. If that is the case, click yes. Once the installer begins to run, you will see a window such as this:
Once you have clicked "Next" in the bottom of the install screen, the installation will begin. This will be a series of screens showing the installation progress and followed by a series of post-install options as follows:
Decide which of the options you would like to leave checked, if any, and click "Finish" at the bottom of the screen. At this point Google Earth will be successfully installed on your computer.