Alright hers how you do it. Start with a blank canvis. Use the gradient tool to create a black and white gradient. Click on filter>>render>>diference clouds. at this point press crt + f untill you find a pattern you like (the black bit is where the lightning will show). When your happy with the difference clouds then press crt + i (this inverts the image) then press ctr l (please note that is not a one but an L...) this opens the levels options window. Drag the middel up faceing arrow all the way to the right and you are left with your lightning. All you need to do now is change the colour (optional). Press crt + u (saturation) and in the window that pops up play around with the settings. Click the colorise check box if you want the lightning to be a colour. BTW if you move the saturation window somewhere where it allows you to see your image then you can change the colours in the saturation window and see what affect that it has. Hope this helps... if you have any questions then email me