Welcome to the BBS, criper! The easiest way to post a location is to create a placemark at the location describing the object (use the "pushpin" icon on Google Earth), then right click on it and do a "save as". This will save a .kmz attachement, which you can then add to your post (the BBS will let you add an attachment when you preview the post). This is much simpler for everyone than just posting lat/long coordinates.
Before you add a new placemark, though, you'll want to turn on the Keyhole Community BBS layer (in the layers menu, bottom left) which will show you any existing placemarks at the location.