If you are satisfied with mere 10% of it then you shouldn't try to learn it from UML book. Rather, you better read a good book on object-oriented analysis or design patterns -- these books provide you with the 10% you are looking for.

If you are nonetheless looking for a tutorial for UML I would recommend this webpage, and especially this essay on UML diagrams (It's not an ad, I personally have no relation to this site whatsoever). Just browse through the diagrams and look at them: they are mostly self-explaining and you can easily understand what they are depicting as long as you are aware of OOP and generally program design and architecture.

If you are satisfied with mere 10% of it then you shouldn't try to learn it from UML book. Rather, you better read a good book on object-oriented analysis or design patterns -- these books provide you with the 10% you are looking for.

If you are nonetheless looking for a tutorial for UML I would recommend this webpage, and especially this essay on UML diagrams (It's not an ad, I personally have no relation to this site whatsoever). Just browse through the diagrams and look at them: they are mostly self-explaining and you can easily understand what they are depicting as long as you are aware of OOP and generally program design and architecture.

Why would I recommend exactly this page? (asked in the comment)

There are several reasons why I liked it more than the others:

1. It presents you an overview table of UML diagrams on the very first page.
2. This table, apart from giving the short description of every UML2.0 digramm, also has a very useful column "Learning Priority" that can help a UML-beginner to identify the most often used UML diagrams.
3. Even though it contains machine-rendered diagrams as well, most diagrams look like being hand-drawn (probably they are hand-drawn). I take it as a sign that modelling can still be done using only your pencil and paper, no need to delve into UML visualisation software in the very beginning.