Hi Patrick,
Collumation means to align the optical surfaces in your scope so that the brightest, crispest images are produced. I think your ETX is collimated at the factory, and shouldn't need adjustment for decades of use(unless dropped, etc.). Here are a few links that explains the collimation process:
Collumation
http://perso.club-internet.fr/legault/collim.html
Collumation 2
http://www.efn.org/~mbartels/tm/collimat.html
Daylight Collumation
http://www.carmelcoast.com/pages/Robin/collim.html
Richard Snow
