Adding a border can be as simple or complex as you want to make it.
Here’s what you can do to make a photoframe. I’ll start with just the basic black frame.
1. Decide on the size of frame that you want (i.e. 4×6, 5×7, 8×10, etc.). Create a new file with those dimensions.
2. Add a new layer on top of the existing background layer.
3. Select the brush and change the brush to be square. Use the “[” and “]” keys to make the brush bigger or smaller so it is the width you want the frame to be (that’s a shortcut key tip to stick in your hat!). Set the color in the paint box to black (the top left box).
4. Place the brush at the corner, hit shift, left click and then pull it across the top. This will create a straight line when you hit the shift key so you don’t need quite the steady hand. Next, do the rest of the edges.
5. If you want it to have an inner edge, then add a new layer underneath the black layer, change the color to white, make the brush smaller and do the same click, shift, drag to the inside edges.
6. A way to add another color layer is to use the rectangular marque tool (looks like a rectangle with dotted lines). Draw a rectangle on the interior of the border. Go to Edit->Stroke. Select the color you want and use about 3 pixels for a thin line. You can play around with inner, outer and center.
7. Now merge the top layers, and make sure you don’t merge with the background layer. Save the file as a .psd file so the layer is saved. The next time you want to add the border to a picture, just hit “V” (another shortcut for the “move” tool) and make sure you have the layer highlighted in the layers box. Click on the frame and drag it to the picture you want framed. Alternatively, drag the picture to the frame psd file beneath the frame and save as a different file.
8. You now have a border that you can drag onto any of your pictures with those size dimensions! You can also use it for different sizes and just resize it on the picture, but if the sizes are off too much, then it can look pixelated.
There are tons of posibilities for adding borders to your pictures. You can download free brushes with squigglies and make frames from those, too.
Have fun playing!