Edit to Add: I probably should of titled this "Understanding gravitational curvature".
Two-dimensional analogy of space-time distortion. The presence of matter changes the geometry of spacetime, this (curved) geometry being interpreted as gravity. Note that the white lines do not represent the curvature of space, but instead represent the coordinate system imposed on the curved spacetime which would be rectilinear in a flat spacetime.
I feel as though I understand this explanation, however, I am uneasy about a little detail.
I would like to have seen another planet in that picture to represent how a planet revolves around another planet.
if I were to dig a hole in a sand box place a ball in the center of the hole and then place another ball outside of the center of the hole I would think the ball would roll down into the other ball. I don't see how the outside ball would maintain a certain distance and then spin around the other ball solely because of the idea of gravity being curved...
How far off base am I?