Basic training for CorelDraw Graphics Suite X5

Where can i get good very basic tutorials on Working with nodes?  I have a CNC plasma cutter and use X5 for simple sign design, mostly wire frame and fonts.  I'm having trouble working with the nodes.  For example what are the red nodes or what ever they are called. I kind of understand the blue nodes, but would like to find a toutorial on making adjustments. Maybe i'm just to new or too old.

Thanks,

Rog