If a shape feature is lacking a vertex, you may add one by using the Add Vertex 
command.
1. To add a vertex, click on the Add Vertex command on the Feature Edit Tab. Select the features you wish to edit if you haven't already.
2. Click a spot on the edge of a feature to add a vertex. If you wish, you may drag the vertex once it is created. In the Map Window, hold down Shift while editing to enable panning with the right mouse button and zooming with the left mouse button (or scroll wheel).
3. Click outside the feature to complete the edit.
