alternating nodes are when your plant is mature enough it will do this. it will start comeing out with leaveslike this, one on one side and the plant looks like it stretches a little and then a leaf comes out on the opisite side from the other.
when your plant starts out the branches grow out side by side when it matures they will start alternating. like foot steps .',',',',',',',',',',',',',',',',',',',',' kind of like those dots. hope this helps.. good luck