Plane of Knowledge is part of the Planes of Power expansion. All starting character areas have a book nearby to click that will take you to PoK. You can try using Ctrl+F and see if there's a PoK zone connection. If it's not in your current zone, it's probably in an adjacent one. What zone are you in currently? If you're in the Gloomingdeep tutorial zone, you can also just say "ready to leave" to Arias and he'll send you to PoK.
I think you need to go the adjacent zone called Blightfire Moors. Near(ish) the zone-in there should be a little piedestal with a book, clicking on that should take you to Plane of knowledge. A more general tip: Press "m" to put up the map. There should be a tab called "zone guide". There you can set your location and a destination, and click "activate path" or something. A yellow glowing trail should show the way. It works in most outdoor zones. I think questions like these should be posted in "the newbie zone". "Player support" is more for technical trouble-shooting.
Fun fact: No one has been to the Plane of Knowledge. The place we all congregate is the city of "New Tanaan" which is located IN the Plane of Knowledge but we never get to leave the city to see the actual Plane.
My theory is that the book on the piedestal is the actual plane of knowledge, and that you just change size when you click on it(or maybe the book changes size...)
I was wondering... Isn't Sunrise Hills geographically located in the Plane of Knowledge too? It is outside the citywalls of New Tanaan... It isn't placed on any atlas, and the zone-guide doesn't work for that zone?