please teach all you know!!!
Almost everything you would need to know is located here.
The basics of noding is simply that the point where an info_node is placed signifies a point in a “mesh” of points where all NPCs can go to. Lines are drawn between said points and NPCs will follow those paths exactly. There are also different types of nodes that signify an action, such an info_node_hint which will count as both a point in the node mesh as well as force an NPC to do a certain action when it arrives at that node. All the different types of nodes are detailed and explained in the link I posted above.