Welcome to the forums, newcomer!
Do you have
this or
this motherboard? In both versions, you have 2USB 2.0 headers(namely F_USB1 and F_USB2) on the motherboard which break out into a total of 4 USB 2.0 ports while you have another header that deals with 2 USB3 ports for the front panel. Make and model of your case? Model for the fans and kit/bundle you're trying to pair with your system?
Please make sure that the system is powered down and disconnected from the wall and display to prevent any mishaps when disconnecting and reconnecting innards. People have been known to fry things when the system was running and they tried connecting XYZ gear to the UISB ports, internally.