Think of a Chinese Game Board, and how you can make jumps. Now think of actual checkers where you capture pieces. How many marbles can you place without a capture possible?
There's one slight rule to make sure this is not easy (without this rule you could just fill every slot):
You cannot place marbles in the outer rim, but you can, when the game starts, capture in that direction. AKA: A marble can jump over another onto the outer rim, but you cannot place it there at the start.
Also, it's important to note that you only use the big part, the outer triangles are unusable.
Note: Any jump can capture, as long as you jump the same distance on the other side as the current distance, and there are no obstructions. Colour do not matter.