you are not supposed to teach the class. the mentor system is for the basics for people in the first 40 hours of playtime. after the first 40 hours they are not longer in the mentor-chat channel and can't get a mentor through the dungeon roulette.

as a mentor you are supposed to explain how a tank builds aggro with first his range attack, than aoe 2-3 times and start rotating aggro combo through the enemys. you have to explain that the DDs should attack the enemy first wich the tank was firt attack with his ranged attack. probably explaining basic rotations for them. explaining that healers should wait until they start healing untl the tank has build aggro on all the enemys and that they should use their dispell if necessary xD

you should know the basics of every role to explain how to play this game. if you join as a healer in mentor roulette you have to be able to explain the tank how to tank and the DDs how to DD. you don't have to be a master in your class with several savage clears and top dps to do so.

so.... after i have now explained the mentors how to mentor: i think am ready too >.>