Chrishonda,
You may (also):
1) Create a circle where you wish to have the dots/circles and cut it where you wish the dots to start/stop;
2) Create one dot as a circle with a black fill and no stroke;
3) Move a copy horizontally to the right (the distance matters little, but it looks more nice if you move it more than 20 dots away);
4) Object>Blend>Blend Options, set the Spacing to Specified Steps with 19 steps;
5) Select both dots from 3) and Object>Blend>Make;
6) Select the Blend from 5) and the circle from 1) and Object>Blend>Replace Spine; that will give you 21 dots, the first and last on top of each other, so it will look like 20 evenly distributed dots.
You may Object>Blend>Expand if you wish to have the dots as separate paths; in that case, you may delete the first or last dot.
If you wish the dots/circles to keep the original orientation (Anchor Points at top/bottom and sides), set Orientation to Align to Page in 4), if you wish to have them rotated set Orientation to Align to Path.