Please tell me how stones jump, and what happens if there is another stone. Can I jump over two stones in one grid?

Stone situated in grid (a;b), then it can move to grid (a+2;b) if it is empty and if there is stone in (a+1;b), stone in (a+1;b) will be taken away;it can move to grid (a;b+2) if it is empty and if there is stone in (a;b+1), stone in (a;b+1) will be taken away; and so on...
P.S. My poor, poor English...

Your understanding is right... But the discription of the problem is not clear enough. I really can't understand at first.

Emm.. is the rectangle solid? That's not clear.