Some courses have sections where you have questions and answers that need to use the drag-and-drop functionality.
Point your mouse to the answer, press and hold to grab the answer, and drop it to the correct term.
The screen will show a green check mark if your answer is correct.
The screen will show a red X if your answer is correct.
You can refer to this wikipedia link - http://en.wikipedia.org/wiki/Drag_and_drop - for more detailed demonstration on drag-drop feature.