Create the Frame
From the Tools toolbar, choose the Magic Wand tool. In the Tool Options palette, set:
Mode = Add
Match mode = RGB Value
Click on each corner piece, shown in black in the image above.
Use the Eyedropper to choose a deep beige colour from the image for your Foreground Color. Select the top layer ('Raster 2') in your Layer palette, activate the Flood-fill tool and flood-fill the selected corners.
Go to Effects || 3D Effects || Inner Bevel with the following settings:
Bevel = No. 1 (1st row, 1st column)
Width = 8
Smoothness = 0
Depth = 20
Ambience = 0
Shininess = 0
Color = white
Angle = 315
Intensity = 50
Elevation = 30
Deselect {Ctrl+D or Selections || Select None). Merge all layers (Layers || Merge || Merge All (Flatten), then go to Image || Add Borders:
Color = Black
Top/Left/Right/Bottom = 10
Symmetric = checked |