You have two controls: a source and a target.
1) Set the target's
Control.AllowDrop[
^] property to true.
2) Start the drag'n'drop process in the source by calling its
Control.DoDragDrop[
^] method. The data you want to transfer is stored in an object that you give the method as a parameter.
3) Use the target's
DragEnter[
^] and
DragDrop[
^] events. The event arguments contain the data that you put in the drag'n'drop process earlier. Do with it as you need.