The Google Earth Community Forums contain thousands of Placemarks which people from around the world want to share with others. Placemarks posted in certain forums will eventually become part of Google Earth itself, in the Google Earth Community Layer, as shown here:

However, when you post a Placemark on the Google Earth Community Forums, it will not automatically appear in everyone's Google Earth 3D Viewer. Your Placemark, along with other new or edited Placemarks, must be added to the Google Earth database in a separate process; this is done approximately every 4 to 8 weeks.

While you are waiting for your new Placemark to be added to Google Earth, you can still share your discovery with your family or friends who use GE. One quick way to do this is to use Google Earth itself to email your Placemark to someone else. To do so, just right-click on your Placemark and select "Email...":

And of course, you can also send them the link to your post here on the Google Earth Community, so they can download your Placemark directly.

Keep in mind that you are creating a placemark that it might become a permanent part of Google Earth! Try to make it both informative and interesting, rather than just making a label. You can read through this thread as well as this one for ideas on how to create a more valuable placemark. And most of all, have a good time while doing so!