mater,
Unless you know how to use RAW format, your best bet is shoot in JPEG, adjust it in Photoshop, (lighten/darken as needed, crop, etc.) then as Tuffcity said, go to Save As (under the File menu) to save the pic to your hard drive. I'd advise keeping all your images in one or more folders you create, so you can find them easily.
Let me know if you have any other questions.
Yeoman