If you don't have access to a scanner, you can also draw an edge (or portions of one), take a photograph of it, and turn that into a border.
key concepts:
threshold
free transform
blending options
Step One.
Press Command-J (PC: Control-J) to duplicate the Background layer, and then press Command-Option-C (PC: Control-Alt-C) to open the Canvas Size dialog. Make sure the Relative checkbox is turned on, and add 1 inch to both the width and the height.
Step Two.
Open the scanned image or photo you took of the edge that you drewas you can see in this example, having great lighting is not important.
Step Three.
Under the Image menu, choose Adjustments> Threshold and drag the slider to the left until you get the result you want. Here you can see two examples of the edge I drew.
Step Four.
Using the Rectangular Marquee tool (M), select one of the areas you'll use as a border. Copy-and-paste it onto your photograph. In this example, I scaled and rotated the copied pixels using Free Transform (Command-T [PC: Control-T]) to add a vertical border on one side. Initially, the copied border will have a white background.
Step Five.
Double-click on the border layer to edit the Blending Options in the Layer Style dialog. In the Blend If section, drag the white slider under This Layer to the left and the white background of the layer will become transparent. If you then press-and-hold the Option key (PC: Alt key) while you click-and-drag the slider, it will split, allowing you to create a smoother edge on the black pixels.
Step Six.
Repeat Steps Four and Five until you have borders on all sides. Chances are you'll end up with more than four border layers, as each side may require more than one piece.
If you wish, you can put the borders into a Group (folder) so that you can show or hide them in one step. To do this, select all the border layers (by Shift-clicking on the first one, then Shift-clicking on the last one), and then in the Layers palette's flyout menu, choose New Group from Layers.
In order to add layer styles to our borders we have to merge them together (otherwise the white backgrounds would come into play). In this example, I duplicated the Group so that I could keep the separate border layers in the original and have a copy in which I could merge the layers. After copying the Group (by choosing Duplicate Group from the Layers palette's flyout menu), I selected the border layers in the Group and chose Merge Layers from the flyout menu.
Variation
In this variation, I added a layer style to the merged border layer by clicking on the Add a Layer Style icon at the bottom of the Layers palette and choosing Gradient Overlay, then changing the Blend Mode to Vivid Light.
If you wish, you can put the borders into a Group (folder) so that you can show or hide them in one step. To do this, select all the border layers (by Shift-clicking on the first one, then Shift-clicking on the last one), and then in the Layers palette's flyout menu, choose New Group from Layers.
In order to add layer styles to our borders we have to merge them together (otherwise the white backgrounds would come into play). In this example, I duplicated the Group so that I could keep the separate border layers in the original and have a copy in which I could merge the layers. After copying the Group (by choosing Duplicate Group from the Layers palette's flyout menu), I selected the border layers in the Group and chose Merge Layers from the flyout menu.
