The north and south celestial poles are two imaginary points and therefore cannot be "discovered".
north celestial pole
The celestial poles are located directley above the Earth's north and south pole.
The movement of the celestial pole is caused by Precession of the Earth's rotational axis.
The earth's axis of rotation points directly at the celestial pole.
The Celestial Poles are the infinite extension of the North and South Poles from the Earth into space. The North Star or Polaris, is within 1 degree of the North Celestial Pole. There is no equivalent star for the South Celestial Pole.
They are the constellations at the celestial north & south poles - Ursa Minor (the little bear) is at the celestial North Pole and the Southern Cross is a constellation near the celestial South Pole.
Yes. For any point on Earth that is north of the equator, the north celestial pole is above the horizon.
A person would have to visit the equator for the celestial equator to pass through your zenith or one would have to be at the south pole for the south celestial pole to be at your zenith. You would not see this, but you could note it.
At the south pole.
To place a celestial pole on your zenith, you would travel to the North or South Pole. Your zenith is the imaginary point directly above your head.
Pole
To see both the north celestial pole and the south celestial pole at the same time a person would need to standing at the equator. The atmospheric haze may interfere near the horizon may obstruct the view.