Parchments and Glyphed Rune Word - PoP Spell Runes
Starting in the Planes of Power expansion pack getting your new spells 61 - 65 is handeled in a slightly different way. The different named enemies of this expansion pack drop two different types of parchments, Ethereal Parchments and Spectral Parchments. Ethereal Parchments are for spells that are level 61 and 62. Spectral Parchments are for level 63 and 64 spells.
There's an additional item too for PoP Spells called a Glyphed Rune Word. This item drops off higher level nameds/raid bosses/enemies in zones that require PoP flags to enter. The Glyphed Rune Word is used for your level 65 PoP spells and as you could imagine is rare to come by.
Once you have one of these items in your possession you'll want to take it to any 1 - 25 Spell NPC in the central library of Plane of Knowledge. Hand it to him and he will give you a random spell back. You can give the item to any classes NPC and get a spell for that class - so if you're a Druid you can give it to Minstrel Eoweril and get Bard songs if you want.
That's really all there is to it - it usually takes 10 - 15 parchments for you to get all of the spells you need (of each parchment type) which is the more annoying part of this process. Luckily though people usually sell the spells they get duplicates of in The Bazaar so check there if you aren't getting lucky at the NPC.
If you'd like a list of spells by class that you'll get I got your covered!