Background light « Background Cover « Photoshop Tutorials

Option 2: This other approach is a little more work, but it gives you more control over the final result. Hit the "d" key to set the default foreground and background colors to black and white, then choose Filters->Render->Clouds. After this, choose Filters->Render->Fibers. You can choose any values at all for the Variance and Strength parameters which will vary the look of your light burst pattern. I used 10 for both values and got this: