Library Tools may or may not be what you are wanting. Library Tools are things like "Rename Move and Copy Files". Also functions that are used to manage cover art, tags, etc.
Those Library Tools require you to select one or more files in order to do those functions. For example you couldn't "add cover art" without having a song, album, etc to add that cover art to.
So, select some files you want operate on, then right click and click library tools and you'll get a whole other menu of options.
On the other hand, if you are looking to manage MC's database (which is also called "the Library"), then you want this path:
Tools > Options > Library & Folders
You might particularly want the "manage library fields" selection on that options window.
Best of luck.
Brian.
