The celestial sphere is used to make it easier to find objects in space.  

     Since the Earth is round, picture the celestial sphere as a hollow glass circle with the Earth floating in the center.  All the stars we see are glued onto the inside of the glass circle.  This makes it simple to attach coordinates to the sphere and find stars or planets.  

     The north and south celestial poles are located directly above Earth's north and south poles.  Since the north celestial pole is located directly above true north, its altitude is the same as the observer's latitude on Earth.  

     The celestial equator is Earth's equator projected straight out into the sphere

     Earth is tilted at a 23 degree angle.  So the ecliptic is at a different 23 degree angle on the sphere.  It crosses the celestial equator at 2 points.  These points are called equinoxes.  The Sun moves along the ecliptic and passes the 2 equinoxes on March 21 (the Vernal equinox) and September 21 (the autumnal equinox).