There are a number of ways to learn about OLAP concepts.  I'm not referring to just slice and dice, or drill and filter.  But understanding the power of OLAP, like the cool capabilities of "prior period" calculations that can automatically apply to whatever level you have drilled to in a time dimension.

One uncommon way (for non-programmers) to learn this is to read a book on the MDX query language.   However, don't choose a big thick book.  MDX is more understandable than you might think, though, if you have a very explanatory, introductory book.  I recently mentioned such an introductory MDX book to a new salesperson for Simba's MDX Provider for Oracle OLAP, and lent him my copy.   And he's half way through it and quite happy with what he is learning!

If you are interested in a gentle introduction to the MDX query language, the book is "Fast Track to MDX, 2nd Ed." by Mark Whitehorn, Robert Zare, and Mosha Pasumansky, Springer, 2002, ISBN 1-85233-681-1