Basically mate, you have to add a place mark over where you want to view. Give it a name, etc etc. Once the place mark is there, hover your mouse over it and right click it. You will be given a list of options, on of which is "Save As". Click Save As, give the file a name and store it anywhere you like. And there you have a .kmz file, which will take anyone who opens it to the placemark on google earth.
You cannot upload it to the gallery as it is not an Image - think of the KMZ file as a shortcut to your own icons stored safely away at Google Maps!!
As boney said, you can email the file to whoever you want, or you can post it into any forum topic by "Attaching" it to your post (see the "Add an Attachment" button at the bottom of the post when you click "reply")
Note that you don't get the option to attach a file if you are using Quick Reply!
If you need any help attaching the file to a post, let me know.