I just downloaded the Pure Tileset tile package and I have no idea how to get it into the quest editor.
noob needs help with new tiles
All you need to do is open it in ZQuest. There should be a new ".qst" file which you can open from the file menu. Just go to File>Open and find the tileset you downloaded. As long as you have taken it out of the zip folder and you opened it with ZQuest, you should be good to go.
If it's a .zpg (which I doubt it is), you'll have to import it as a Graphics Pack.