As mentioned this is a great book that covers what you do really need to know: How and Why Astrology even started.
Here's the link to the book The Astrologers & Their Creed by Christopher McIntosh https://amzn.to/2HCw7ok
Here's Dr McIntosh's Uni Page:
This is the piccie from the book showing the ecliptic:Sun's apparent path (among the stars) through the year.
And the Equator : imaginary line around the Earth at equal distance to the Poles
Quote from page 24:
These points are what we would now call the solstices and the equinoxes. The diagram below explains these terms more clearly. The sphere is the Earth and the horizontal circle round it represents the equator (imagining that the Earth's axis is vertical). The tilted circle represents the ecliptic, that is the path that the Sun appears to trace around the Earth during the course of a year. The equinoxes are the points where the ecliptic crosses the equator, once in the spring and once in the autumn. These are marked as E1 and E2 (respectively). The solstices are the highest points of summer and winter and are shown as S1 and S2. If one lived in the northern hemisphere S1 would be the summer solstice and S2 the winter one, and vice-versa for the southern hemisphere.