If dreamed you that you are in library, then in reality you do not accept that circle of contacts which you have. If you accidentally appeared in library, then in real life you quite often give yourself not for the one who you are is actually.
Be sure and keep any other thoughts out of your mind before drifting to sleep as a cluttered mind can decrease the chances that you will remember your dreams upon waking. Also, focusing on remembering your dreams upon waking in the morning is another very important thing. This sounds very easy, but is often hard for some to do. Interpret a dream by "dictionary dream of interpretation"
When you very first wake up, simply think about your dreams. Don't allow your mind to drift off to other things, just lay there and think about the things you dreamt about the night before - dictionary dream meaning.