Create a new document in Adobe Photoshop. A window will open that will allow you to adjust the settings of your document. In the format section, select the option that matches the dimensions of the video file format you are working in. For example, if you are working in standard definition, choose the format that is 640 by 480 pixels. Also, set the background settings to "transparent." Then click "OK."
Select the line tool. In the Photoshop tool bar, select the line tool which is labeled with a diagonal line symbol. At the bottom of the tool bar is the color selector. Click on the color selector and then select a neon color, such as a neon green or purple, that you want to use as your lightsaber color.
Create your light saber. Using the line tool, click and drag your mouse on your Photoshop document. This will create a line. The further you drag your mouse, the longer the line and thus the longer your ligthsaber. In the upper left hand corner of Photoshop there are line tool settings you can adjust. Change the line thickness until your lightsaber is as thick as you want it.
Add the lightsaber glow. The layers menu is located in the lower right hand side of Photoshop. Double click on the layer that was created when you used the line tool. This will open up a window with additional settings you can use to manipulate your line. Use your mouse to check the box labeled "outer glow." The outer glow preferences will then appear. While you are adjusting the glow you will have the ability to preview your line. Choose to make your outer glow white and then adjust the noise and thickness levels to your liking.
Export your lightsaber. In the file menu of Photoshop, click on the option labeled "save as." Choose to save the image as a JPEG and name the file "lightsaber."
Open the lightsaber file in your video editing program. Open your video editing program. Then, in the file menu, click on "import." A search window will open that will allow you to search for your lightsaber file on your computer. Find your lightsaber file, select it and then click "open."
Add the lightsaber to your lightsaber scene. Because you chose to have no background in your Photoshop file, only the lightsaber will appear in your video editing program. Add the lightsaber file to your video editing program timeline. Then, using the control functions in your video editing program, align the lightsaber in your actor's hand so it looks like he is holding it. You will then have to adjust the lightsaber's position, frame by frame, so it follows your actor's motions throughout the scene.