Do you want to know how it's done? Learn how to use Photoshop the easy way!
I have seen many Photoshop tutorials on creating lightning. Most of them seem to use the difference clouds filter to achieve this. Granted, it is a cool lightning effect. The problem with it for me is that it is so random. You really have no control over which way the lighting is going to go. If you are looking for a great burst of lightning, and direction doesn't matter, then this is a good way to go. If however you are looking to control which way your lightning is going to go, in a just a few easy steps, then this tutorial is for you. Let's get started. If you prefer check out the Create Lightning Video Tutorial.
For this tutorial, I am going to use a black background. You can of course do this with any background you like.
Open a new document of whatever dimensions you like, and fill the background with black. Edit/Fill/Black. I am using 500 X 375, resolution at 72 pixels/inch. Create a new layer by selecting Layer/New/Layer. Now we need to select the Brush Tool.
Select a hard round brush, and set the Master Diameter to 4px. To get to this window right click on your document.
Set your foreground color tile to white, and paint a jagged line in the direction you want. Also add a couple of branches. You almost can't screw this part up, but just redo it if you don't like your first bolt.
Next you will want to select the eraser tool. Zoom in a bit and give the bottom of the lightning bolts a nice pointed end by erasing some of the bolt.
Now go back to your Brush Tool and set the Master Diameter to 2px. Draw all the little fingers that you would also see on a lightning bolt. If needed, give these branches a nice point as well.
Now we need to duplicate this layer. Choose Layer/Duplicate Layer. With this new layer selected, go to Filter/Blur/Gaussian Blur. I set my radius to 5.0. The higher the radius, the more outer glow you will get on your lightning. Now duplicate this layer, and then duplicate that layer. So you should now have a black background layer with four lightning layers on top.
You can also create a cool effect by adding some color. Make sure that the top layer is selected then choose Layer/Layer Style/Blending Options. In the Blending Options window check mark the Color Overlay box and change the color to whatever you want.
How about a nice blue lightning bolt.
Or Pink? Anyway, you get the idea.
Here is a before and after of a picture I added some lightning to.