Learn how to create the infamous disco-lights!
Step 1. Open a new document with a predesigned spotlight or draw one yourself like I did;
Step 2. With the pen-tool, draw a shape like the light I drew in the image below;
Step 3. Right click and select "Make Selection";
Step 4. Grab the Gradient-Tool and select a gradient from white to transparent;
Step 5. Duplicate the layer and go to Filter>Blur>Gaussian Blur of 3 or 4 pixels;
Step 6. Lower the opacity of the blurred layer to 66% and the opacity of the original to 33%;
Step 7. And then you are done and you can use your knowledge for the benefit of creating a spotlight!