Finding inorder successor
Please give clear meaningful name. Your class name is Successor... now who's successor? yours? king Luthar's? who's? See the concern. I think BinarySearchTree is the apt. name for the class.
In makeBinarySearchTree you are creating a Binary Tree, so someone seeing your code will think it as a factory method, so better make it that way.
You can make your class generic but that's not a big deal for now but in future keep this in head and try to find always general solution for any given problem.
Someone using your getSucessor method(should be getSuccessor) will always get the inorder-successor. Now what if someday someone want to find preorder-successor or preorder-successor, what will you do then?


Otherwise your code is good and self-documenting.