Step one: Workspace
First you need to find what you are reflecting, and be sure that it is already cut out (no background). This works especially well with a screenshot of their program iTunes, so that is what I will demonstrate with.
Now, create a new file that is able to support double the height of the object.
Step 2: Fill and Copy Object
Fill the background with any colour you like, but a sleek black or white is always great. Then drag your object onto the canvas and position it towards the top of the canvas. Hint: if you are using a gif, you may need to use the rectangular marquee tool to select the entire image, then move it.

Step 3: Copying the Object
Now right click on the layer the image is on and select Duplicate Layer. Go to Edit>Transform>Flip Vertical. With the move tool selected (dark mouse) hold shift and move the image so that it is exactly under the top image.

Step 4: Creating the Effect
First, go to the gradient tool and make sure it is set for Foreground to Background, and press D to reset the FG and BG colors to default (black and white).
Now, for the effect you need to go to the bottom of the layers panel with the copied layer selected and click Add Vector Mask (it looks like a box with a circle in it. This tool is somewhat complicated and somewhat simple: it makes the white visible, the gray less visible, and the black invisible. Draw the gradient now by dragging from the top of the copied portion to the bottom of the copied portion. Next, to make it more realistic, bring the opacity of that layer down to 50% (in either blending options or on the top of the layers panel). And, since this is a true fade out, you can have the background be anything you wish and it will still blend in and look great.

Also, you can select both layers (click one and shift click the other) and go to Edit>Transform>Perspective. Grab a corner and play around with it! (press enter when finished or escape to re-do) Here is what I did with that.












