Choose View - Toolbars - Drawing to open the Drawing toolbar, if it is not already open.
Drawing objects can be subsequently edited and modified. Drawing objects created in this way are vector graphics, which you can scale freely without any loss of quality.
To create a rectangle, click the rectangle icon and move your cursor to the place in the document where you want one corner of the rectangle to be. Press the mouse button and hold it down while dragging to the opposite corner of the rectangle. When you release the mouse button, the rectangle is inserted in the document. It is selected, and you can edit its properties through the context menu.
To revert to normal mode after creating and editing draw objects, click in an area of the document containing no objects. If you see a drawing cursor, first exit this mode by clicking the Select icon.