Thank you, Andy.
I learned Xpresso node by node, playing with it.
The typical suggestion would be:
What is in the "wires", knowing the formats, Real, Integer, Vector, to start.
Then pick some nodes and mess around. You know that everything has a learning curve, so take your time.
When hitting a roadblock, please ask! I learn from questions as well. So, never a waste of time for me.
Enjoy