How do I add a border to a picture?

1. If all you want is a skinny black border, go to File > Print Preview. At the bottom of the dialog that appears, click the checkbox next to Show More Options. Click the Border button. Then enter a width. The maximum is .15 inch and the only color is black.
2. If you want a wider border or a different color and don’t mind covering part of your image with the border, choose Select > All followed by Edit > Stroke. Enter the width that you want for your border. Click the color square to open the color picker and choose your color. Where it says Location, click the Inside radio button. Then click OK to apply the stroke. Choose Select > Deselect to end the selection.
3. To add a border without covering any of your picture, first set your foreground color to whatever you want to use for your border. Use the Swatches palette, or the color picker. Once you’ve picked your color, press the X key on your keyboard to make that color your background color (the X key switches your fore and background colors).
4. Enlarge the window around your picture to be larger than the image (so you are seeing background gray between the image and the window frame). Do this by hovering your cursor over the image window’s border until you see a double-headed arrow. Then drag the window border to enlarge it.
5. Take the crop tool (in the toolbox) and drag a crop box around your entire image (click above the top left corner of the image and drag beyond the bottom right corner).
6. Press both the Alt and Shift keys and drag down and to the right (outwards) on the bottom right corner handle (the little square you’ll see on the corner of the crop box) to enlarge the crop box to the dimensions that you want for your border (the current background color will be added to the enlarged canvas).
7. Click the big check mark on the crop tool’s options bar to accept the enlarged canvas.
8. The added canvas will, of course, enlarge your image dimensions. If you don’t want this, go to Image > Resize > Image Size after you’ve added the border, and follow the directions given on this page for resizing.