If you want to draw the rectangle using snaps, make sure that the End Point Snap and/or Between Ends Snap are turned on.
Position the cursor at one of the rectangle’s corners. Press down your left mouse button. Holding down your left mouse button, move your mouse. As you move your mouse you will see the rectangle being drawn. When you are satisfied with the rectangle, raise your left mouse button.
Click to undo.
Rectangles are drawn as polygons.
If the rectangle is displayed in green, vectors are set to display by type. Press C to toggle between displaying vectors by color or by type.