Well, me personally, will tell them to read
this as part 1 and
this as part 2 so they get an explenation what is Chaos Reputation and why it is important. And then at part 1 and 2 they will also find how to do the instances and kill the bosses there as per their evel. And if they have something unclear I will nicely answer their questions.
I am trully sorry that I can not write anything here but I have done it already before
And yes, this is the way I explain players how to do Chaos Invasion and Destroyers Chaos Reputation