If you don't have $1,500 or so to spend on Photoshop there is a great free online photo editor called Pixlr. You can find it at Pixlr.com, or just use it below. Just click upload an image, you can crop it, rotate, and add effects to make it look fabulous. Then just us Save the image back to your desktop by dropping down the menu under file.
Here is their online user guide: http://ictpublish.com/pixlr