WikiHow is a site where anyone can add instructional guides on pretty much any topic you can think of. There's lots of good information (in between the tons of Google ads) from How to Teach Yourself Piano to How To Treat A Snakebite – although the usual caveat about the guides being user-submitted and editable by anyone applies.
A search for “library” reveals a bunch of interesting guides – from How To Check Out A Library Book to How To Write A Note Commending Library Staff.