Although we say we are "importing photos into Elements," your photos don't actually live inside Elements. They are still files on your hard drive, just as they always have been. Photoshop Elements Photo Organizer just indexes them. You can think of the Organizer catalog a little like a computerized card catalog that you would find in a library. The catalog is just an index or database, but the actual books still sit on shelves in the library. Part of the job of a librarian is to track everything that happens to each book. They do this by way of the catalog. Similarly, you are the "librarian" of your photo collection, and Photo Organizer is the catalog where you index and track everything ahout those photos.
Imagine if someone snuck into the library and removed a book without going through the librarian. That book would be gone, but of course the library would still have a record of it in their catalog. The same thing happens when you delete, rename or move photos on your computer outside of the Photo Organizer. This results in missing files in your database. You'll still see a thumbnail for them, but they will appear with a missing image icon. Organizer does a pretty good job of relocating photos you have moved, but it can save time if you do your file management directly through the Organizer using the File menu commands or via drag & drop in the folder tree when you switch to Folder Location view. Deleted files, of course, won't be found and you will need to delete them from the catalog eventually. Again, it's best if you delete unwanted files directly from the Organizer.
The main point here is to understand that the photo files on your hard drive are not duplicates. Never delete a file on your hard drive thinking it will continue to existing inside Photoshop Elements.
That said, it's about time we got started importing and organizing! If you've already installed Elements, you may have already imported your photos and begun organizing with tags and collections. If that's where you're at, you can skip reading the importing steps that follow. If not, you have two choices for initially populating your catalog with photos from your hard disk:
If you were not diligent about storing all your photos in a few main folders, you can have Elements search your entire computer for photos. This has the potential of importing a lot of junk, so if you know more or less where you photos are located, you'd be better off using the import from files or folders method.
--> Importing Photos by Searching Your Computer
If you keep all your photos under My Pictures, or have a good idea which folders on your computer contain your personal photos, it will be faster and easier to acquire your pictures using the "From files and folders" method. This is also the option to use for getting photos you have stored on CD or DVD.
--> Importing Photos from Files and Folders