Good luck on your first cook! You must get yourself a copy of Gary W's book "Low and Slow" - it is the perfect companion to the WSM.
On your first cook, just a suggestion, sit down ahead of time and plan out your cook, working backwards from when you plan to serve your food (allowing some time to account for the fact that you don't cook by time, but by "its done when it's done).
Have you picked out your recipes yet!!
Good luck and let us know how it goes.
Pat