Creating Figures.

To create a new figure you may choose from the toolbar one of the following tools: Line, Sector, Arc, or Spline. 

Then using a mouse you draw a segment. To add another segment to it, start drawing from one of the endpoints of the already existing one. This will lengthen the geometry of the figure. If you start drawing a segment at any position with Ctrl (Cmd) held down, this segment will be assigned to the currently selected object, starting a new geometry. So, the object will consist of two (or more) separate geometries, but it's still one object.

If you hold down the Shift key when drawing, constrained drawing mode switches on. The way in which constrained segments behave depends on the segment type.

Lets describe the basic segments.

LineTo: is a linear segment. It can be created with the Line tool. To constrain a line to any 45-degree angle, hold down the Shift key as you drag.
Note: press Ctrl+3 to switch to the Line tool.

ArcTo: is a sector of circle. It can be created with the Sector tool. The direction in which you first drag the mouse determines which way the curve bows. The point where you release the mouse button defines the other end point of the sector. To change the direction in which the curve bows, hold down the Shift key when you drag.
Note: press Ctrl+4 to switch to the Sector tool.

EllipseTo: is an elliptical quarter-arc segment. Use the Arc tool  to create it.
Note: press Ctrl+5 for the Arc tool.

Spline To: is a smooth curve (also called spline). It can be created with the Spline tool. This tool works like a pencil on paper, the only difference is that the curve results is smooth rather than jagged. Once drawn, the spline is easy to modify by adjusting its vertices and adjustment handles.
Note: press Ctrl+6 to switch to the Spline tool.

Besides single segments you can also draw some widely-used complex figures: rectangle, ellipse, text. Use the corresponding toolbar buttons for each of them.

Rectangle:  creates a filled rectangle. Drag the mouse to change its size. By holding down the Shift key as you draw, you constrain the rectangle to a square.
Note: press Ctrl+7 for the Rectangle tool.

Ellipse:  draws a filled ellipse. Drag the mouse to change its size. By holding down the Shift key as you drag, you constrain the ellipse to a circle.
Note: press Ctrl+8 for the Ellipse tool.

Edit Text:  creates a text box. Drag the mouse to change its size. If you are holding down the Shift key as you drag, the text box results in a square. After you release the mouse button, the Edit Text mode switches on.
Note: you can also use the F2 key to turn the Edit Text mode on.