I need help with the collision polygons and physics

Hi. So I know that I can add sprites and make them solid. But in the case if I add a ball, or wave-like solids, I need help. I know that once I make it solid, if I toggle to see the collision polygons, 4 corners will show. How can I make so that there are more corners? How can I make it so then I can make a sine wave hill terrain collision smooth?

You mean add more collision points, just double click on the current point to add more.