Hey

I am new to Java. Im reading a course of 10 weeks where i am to learn the basics of UML and Java.
Our group assignment is to first build a class diagram of a library in UML and then transform that into java.
At this stage i have not really started focusing on java atall, im only at UML and class diagrams.

I hope it is alright to mix in a bit about UML at this forum... could not find a good UML community.
But here goes

I have this UML diagram that i have done
Screenshot by Lightshot

It is for an library system.
User database, admin(librarian), loaning process and the media database (books, cd, journals)

Does it look ok, any comments?
Have i missed something?
Is it weird and completely wrong?

Im looking for a bit of feedback to know what to do next and if the stuff i´ve done is right or wrong.