Carefully unplug the plastic piece at the end of the wire from the motherboard at the highlighted point.

Carefully remove said plastic piece from the end of the wire bundle at the end of the wire.

Do not lose this plastic piece, as it plugs the fan into the fan's power supply.

Be very careful to avoid damaging any of the components listed above. If any of these parts are damaged, the fan, if not the computer as a whole, could be irreparably damaged.