Many ttk objects are just thin wrappers over existing Tkinter objects, so the Tkinter descriptions will be what you are looking for. One good place to look is An Introduction to Tkinter (on effbot.org). There are other good references listed at the top of the main Tkinter page in the Python docs (the page before the one you linked to). The New Mexico Tech docs are quite extensive and recently updated too.
To get a lower level view of how ttk objects are based on Tkinter objects, look in the ttk source code in C:\PythonXX\Lib\tkinter\ttk.py. Here you'll see that ttk.Frame is just based on a tkinter widget and there are no further methods or attributes defined.
The "sticky" parameter is actually part of the grid geometry manager and says what side of the parent container an object should "stick" to, with options given as compass points. "NW" means "top left". The effbot Grid page gives a good breakdown of all of these options.