How can I plug the nzxt fans into the motherboard and which port to use?
they should have 2 separate cables.
one is a 4-pin PWM fan cable, the other a 4-pin RGB cable.
just Google search for the difference, you should find plenty of images showing them.
your motherboard should have multiple 4-pin PWM headers,
check the manual for an image showing their location(s).
you would have to verify if your motherboard has RGB headers, and how many.
but if so, you can locate them the same way as the fan headers.
just be sure you're not plugging them into 3-pin
aRGB headers.