Concept maps are visual representations of how concepts on a particular topic relate to each other. Nodes and links are the symbols used to create a concept map.
A concept map has to contain all of the important concepts for the topic, and it has to make sense to you. You could ask a friend who is working on the same topic to look at it to see if you missed anything, or you could ask your instructor to look at your map. You could also use a checklist to assess your map yourself.