Connect the shapes. Open the Shapes menu from the Insert tab. Select the line style that most suits your needs. Hover your mouse over the first shape. You will see small boxes appear on its edges that show where lines can be connected.
Start the line in the box, and drag it to the second shape.
Small boxes will appear on the edges of the second shape. Place the endpoint of the line on one of these boxes.
The shapes are now connected. If you move one, the line will stay connected, and adjust its angle appropriately.
Add comments to connecting lines by inserting a Text Box, available from the Insert tab.