I don't have a sketches folder either.
You do. If you select File->Preferences, it will show a dialog box with the path to your sketchbook folder. Note the actual name of the folder is "Arduino" by default.
My path to the libraries folder is:
That is the system libraries folder. You don't really want to install your files there. Although it will work (for now), when you install the next revision of the Arduino IDE, you will have to re-install all your libraries. If you install them in the sketchbook libraries folder, they will still be there when you update the Arduino IDE>