Whats the relationship between the celestial sky movement and the Sun movement relative to us?
The (imaginary) celestial sphere with the “fixed” stars stuck to it rotates around the Earth once per day. It may help to think of this as a “backdrop” which is quite large and far away. Now imagine the Earth and Sun together at the center of the celestial sphere. From the point of view of someone on Earth the Sun rotates along with the sphere every day, but unlike the stars, the Sun is not completely fixed to the sphere. The Earth goes around the Sun once per year. So, from the Earth, it looks as if the Sun is slowly going around the Earth, against a backdrop of stars. It looks therefore as if the Sun is moving through the constellations. Figure 2.14 in your text may help with this visualization (although it might help to imagine the celestial sphere backdrop as farther away than shown).
