Open /New 500x500 rgb, white, 72 ppi, Add a new Layer by clicking Layer=>new Layer. Hit the D key to set black as your foreground color. Using the fill tool, Fill with black
Open Image 500x500
Click Select=>All, then Edit=> copy. Then click Edit=>paste to make your images a new layer.
Open new layer by clicking layer=>new layer. Select the Polygonal lasso tool. Click once at the right corner of layer. Release mouse and click at about 400px across on the bottom. Release mouse and click at the bottom right corner and finish by clicking at the top coner to make triangle.
With the foreground color black using bucket fill the triangle.
Create a new layer. Click rectangle marquee and make a rectagle of about 100px bon top to top 500 px on bottom.
Click the D key to set forground and background colors. Click on gradient tool....Foreground color Black...holding shift key drag horizontal across rectangle
Select Edit=> Transform=> Perspective. drag top corners till they meet in middle
Select/ deselect
Move tool rotate and move and stretch and compress until it joins with the black triangle on the left edge of the triangle.
With Ellipticle marquee make a circle about 300 pixels in diameter. Make sure gradient layer is highlighted.
By clicking inside circle you can drag that circle down the gradient layer, drag the circle till the top of the circle touches both corners of gradient triangle.
Click delete key, and deselect
Now double click on gradient layer / add some
drop shadow..I use
Multiple
opacity 75%
Angle 90
Distance 20
Size 10
Now if you want you may change the color of black triagle for different color or replace it with another image...and so on.
You may also merge the 2 triangle and drag them lower...you just need to repeat the Eliptical marquee and drop shadow part of the tutorial on the gradient layer.