Here is an equation for a sphere: (x-18)^2+(y-5)^2+(z+11)^2=36

give the coordinates of two points on the sphere.

I know how to find coordinates on a circle using the equation (x-h)^2+(y-k)^2=r^2 but I can't figure out how t do it with a sphere.

Well, you know the sphere has its center at (18,5,-11) and has radius 6

So, how about points lying on the axes, as measured from the center?

(12,5,-11) (24,5,-11)
(18,-1,-11) (18,11,-11)
(18,5,-17) (18,5,-5)