The Personal Data section of the control window is where your placemarks, datasets and website bookmarks are managed. Managing placemarks is similar to managing files on your computer.
Your personal data can consist of simple placemarks, website bookmarks or complete KML dataset links. Create a set of hierarchical folders and store your items in categories that make sense. There are no restrictions on the number of items in a folder or the depth of folder nesting.
You can gather a lot of geographical data from the embedded web browser. There are several websites that routinely publish information about new and interesting KML files.
Moving items around in your personal data is as simple as dragging and dropping them. You can also drag placemarks right from the globe into your list. Website URLs and KML/KMZ files can be dragged into your personal data folders as well. Look for the insertion bar (see below) to determine where the item will be located after dropping it.
Clicking the "+" button in the lower left will add a new placemark at the current location and open a Placemark Window to edit your placemark settings.
To edit or delete the selected placemarks, select the gear popup item or use the commands in the Edit Menu.