Post a picture of the inside of your computer. It will help us get a better look at it and maybe we can spot anything that needs to be plugged in or not. But if nothing happens (such as no sound/clicks what-so-ever), at the top of my head, 1) Did you plug it in? 2) There should be a power switch on the PSU, is that in the On position? 3) Did you connect your power switch up right? (Those tiny pins and tiny connectors can be a hastle).