If you draw a shape such as a circle or rectangle, you will not be able to edit its nodes until you convert the object to curves. (Only spirals, freehand lines, and bezier lines are initially created as curved objects.)
Select the object using the Pick Tool.
Choose Arrange > Convert To Curves, press, or click Convert To Curves on the property bar (Figure 6.8).
Figure 6.8. Use the Convert to Curves command or icon to change a defined object to one composed of curves.