You can save the kits/samples where ever you like on your hard drive, but Maschine does also have a default user area. E.g. for a Mac, look for the folder ….Documents/native instruments/maschine 2/ (I assume PC is something similar. Please contact me if you know this so i can update this section) The samples from sample packs i normally keep in my own sample folder and you can import them into maschine through the maschine browser. That way you can tag them while you import them too.