Secondary profession change?

[Cocotroid]

I've read about it here before and I'm thinking about it for my ranger but I have a couple questions:
1. Where do you change it in the first place?
2. How many times can I change it?

[Wandalf]

You can change it in the Crystal Desert. You have to visit 3 outposts where you will eventually be given quests (right after your reach Droknar's) to change your seconday profession.
You can change secondary as much as you like.