Step 2: Pull down the Filter menu to Blur-Motion Blur.
Step 3: Change the distance to 500 pixels and the motion blur direction to horizontal.
Step 4: Create a layer mask on Layer 1.
Step 5: Set your foreground color to black and the opacity to somewhere between 60%-75% and paint in the layer mask to reveal the underlying layer.
Step 6: Optional- Pull the Filter menu down to Distort-Diffuse Glow to create a spooky glowing effect. (Edit: I wrote this tutorial using an earlier version of Photoshop. To access Diffuse Glow, you now need to open the Filter Gallery from the Filter menu)
Step 7: Create an Adjustment layer for Hue/Saturation, click the Colorize button and adjust the Hue and Saturation to make a spooky duotone.