Select the Crop Tool
Choose the Crop Tool by clicking on it.
Create Your New Composition with the Marquee
1. Click and drag to place the Crop Marquee on your image . The area outside the marquee will be darkened; this area will be removed from your image when you complete the crop.
2. Adjust the marquee by moving the handles.
Rotate the Marquee
Image 3: Photoshop 7 Crop Marquee Rotate the marquee if desired. This is the most exacting part. You must pull your mouse pointer away from the handles a short distance. When you see the rotate symbol Curved Arrow, click and drag to rotate the marquee.
Though you might find this frustrating at first, play with the mouse and try different distances from the marquee until you see the mouse pointer change to the rotate symbol
Sometimes rotating the marquee can alter a photograph's composition more than you might expect. Perhaps this aspect of cropping a photograph could be referred to as taking a photo within a photo!
Hopes this help.
Try these links;
http://wings.buffalo.edu/computing/Documentation/win/PhotoshopCS.htmhttp://www.thegoldenmean.com/technique/crop3.html