I do, but its broken, and only spins for 1 second when the Power button is pressed (Well, more like 2).
OK, well the fan is cooling the CPU, so if the fan is not running then the CPU is getting too hot and shutting down.
Let me ask you, have you grounded yourself before touching your motherboard? Do you know what I mean when I ask that question?
If the answer is no then you might want to find someone, who knows a bit about computers, to show you how to fit your new fan/heatsink correctly. Or take it to a repair shop and ask them to show you how.
It may should harsh but actually I'm trying to help you. You see eventually you are going to break something, but you wont know what, and then your really going to get frustrated trying to fix something where you don't know what is broken.
Unless you have lots of money and time...