How do I add editor extensions to Unity?

I found this collection I wish to use, but I cannot find anything anywhere to explain how to actually make them work: http://forum.unity3d.com/threads/paraphernalia-open-source-extensions-property-drawers-editor-scripts-and-utils.244697/

I tried just adding them to the Assets folder but that doesn’t work, and I’m at a loss as for what to do.

All editor extensions go to a folder called ‘Editor’ which can be placed anywhere in your assets folder.