You wanna make sum cool rays of light or Lightning effects? Lets start then!

1. First open a new document. Set it to RGB. As you can see, the size doesn't matter too much. But if its under 90x90 pixels it normally doesn't work out. Put it to 500x500 for now.
2. Press D (resets colors, puts black infront of whte). Fill your document with black. Go to filter > render > clouds. Then, filter > render > difference clouds. then press Ctrl+I
3. Now press Ctrl+L which will take you to Levels. There are 3 slider tabs in the Levels configuration, take the middle one and slid it all the way to the right. Press OK
4. You should see some funky lightning now. The lightning tutorial is complete. Continue on for the Light Ray tutorial. If you want you can colorize it by pressing Ctrl+U (hue/sat) and checking off the Colorize box. Then move the sliders to get a nice color.
5. Do steps 1-3. Don't colorize yet (you can if you want, but I didn't). Go to filter > blur > radial blur. Set it to Zoom, drag the zoom area to the top right or left corner (I used top right corner in mine), set the amount to 100 and quality to best
6. Now you should have a pretty cool Light Ray effect, but to top it off go Filter > Render > Lense Flare. Drag it to wherever you set the Zoom to; for me its in the top right corner. Set lense to 105mm Prime, and for the brightness I used 152, but I think it varies with the size. Make it look bright... thats all you should do. Press OK
7. Now, go Image > Adjustments > Color Balance (ctrl+B). You will see 3 boxes with the default number in them; 0. You can fool around for different colors, but i used 0,+40,+100. It should make a blueish color. Thats your own choice though, you can change it to whatever you think looks good.