Turn your PC off and unplug the fans and boot in to windows like you normally would.
Take both side panels off your case and trace the fans back to the fan headers on the board that look like this:
White with 3 or 4 metal prongs sticking out of it. Sometimes they arent white but black.
depending on your set up, you may need to remove your graphics card to get to one of them. You should also be able to get the model number of your board and download a manual for it and that will tell you pretty much everything about the board you'll need to know for a lot of things.
If you dont have any confidence about attempting any of this then the only answer is to take it in to your nearest repair shop and have them do all the troubleshooting and part swapping for you unless you have a friend or know of someone local who is willing to do it for you.