First create a document of format A5. Then go to menu photoshop Image-Image Rotation-900 CW. Now create guides margins along the edge 1 cm
To enable guides, press Ctrl+R.
Take the tool Rectangular Marquee Tool and select the area which we just did.
Invert the selection – Select-Inverse. Create a new layer, go to menu Layer-New-Layer. Next, you need to fill the selected area with the tool Paint Bucket Tool.
Remove selection – Select-Deselect and select Blending Options in the generated layer. Experiment settings and press the OK button. That’s what we’ve got…
If you want to create a frame with rounded corners, you need to choose the tool Rounded Rectangle Tool and enter the radius of their values. For example, 10-15 pixels.
Next, click the right mouse button on the rectangle and select Make Selection. Then invert the selection by pressing the key combination Shift+Ctrl+I and go to the layer with the image (default is the background layer).
Click the Delete button on the keyboard.
Now go back to the layer we just created a rectangle and remove the visibility of the layer and delete the selection – Ctrl+D.
And finally, option 3 to create a simple framework:
Go to menu Image-Canvas Size and select in settings the width and height the required dimensions for the new framework. To background automatically became the color that you need, in box Canvas extension color to put the color that you wish.
In this case, I chose a color from the photo itself (color of leaves).