178712 Image Auto switcher

I need a simple java script Image Auto switcher that would work for my php friend my adder site when someone clicks on the picture it will open a new window and the image i clicked on will switch to the next picture i have a file attached but it doesn't work with what i want this to do. and i don't want to have to pay anything just to get this done cause i don't really have the money right now this should be simple but i just dont know much about javascript.