There are three saving commands in Photoshop: "Save", "Save As" and "Save for Web".
§ 1. Open an image from the "ASAP" folder - for example, "focusing.jpg" - and edit it to your taste.
§ 2. Pull down "File > Save As" or press [Ctrl+Shift+S] keys to open the "Save As" dialog.
§ 3. In the dialog box, select the PSD format as it is shown in the movie and click "Save". The "focusing.jpg" has been saved as "focusing.psd". Now we can continue working with the document without affecting the original image from the sample folder.
§ 4. Make some changes to the document - paint, clone, or type something.
§ 5. Have you finished? I'm sure it looks great now! Let's save it again using "Save" command. Just press [Ctrl+S]. Your efforts are saved now to the "focusing.psd" file.
NB PSD (Photoshop Document Format) is a "working" - that is not intended for publication - format saving your picture without loss of quality. Alongside with graphic information it can store layers, masks, and other auxiliary data.