Open your picture in Photoshop. When you have the picture edited and looking how you want it then you can frame it.
From the drop down menu across the top select Image then Resize then Canvas Size... you should now see this screen or similar.
The first area I circled shows the existing size of your picture. By increasing these numbers you tell how much bigger you want the "Canvas" to be then the picture. (How much it sticks out the sides).
The second area I circled is where you select what colour you want the Canvas to be.
You can add as many canvases as you want, what ever colour you want and what ever width you want.
Have fun, play around with it some! I look forward to seeing a framed picture!