Change the Shading Outside My Border?

Once you have the Crop tool selected (C), go up to the Options Bar, click on the second icon to the right of the word “Straighten” (it looks like a gear), and a pop-up menu of options appears. Near the bottom of that menu are the Crop Shield options, where you can adjust how dark (or light) the area that you’re cropping away appears onscreen before you crop it (by default, it’s shaded to 75%). You can change that amount (making it as dark as solid gray, as I did above, to making it completely transparent) using the Opacity slider. You can also pick a different color by choosing Custom from the Color pop-up menu (which might be helpful if you’re cropping a black-and-white image. Personally, I don’t ever change this color, but don’t let that stop you, if you want to).