From the Tools toolbar, select
the Pen tool 
.
From the Tool Options palette,
select the Edit Mode 
.
Select a node and drag it to a new position, or press the arrow keys to move it one pixel at a time.
Moving a node alters the shape of a vector object. If an object has more than one contour, move a contour by moving all of its nodes. Move the path to move the entire object.
Node moving tips:
While you drag a node you can constrain its line segments to 45 degree
increments.
Hold down Shift to constrain the previous
segment.
To move a node:
From the Tools toolbar, select
the Pen tool .
From the Tool Options palette,
select the Edit Mode .
Select a node and drag it to a new position, or press the arrow keys to move it one pixel at a time.
Adding or Removing Nodes on a Contour