There are plenty of manuals, tutorials, and demonstration notebooks about Mathematica on the WWW. Our local material is organized into subsections according to the menu on the left.
From time to time, usually at the beginning of each term, a two day crash course is offered to TU/e students and staff.
The Dutch Mathematica reseller CANdiensten offers a free introductory course at the TU/e campus from time to time.
Wolfram Research, the maker of Mathematica, provides a wide selection of teaching material.
Every copy of Mathematica comes with a big pile of documentation built in. In version 5.2 and earlier this documentation is organized in a HelpBrowser that one can access via the Help menu of Mathematica. In version 6 and later the HelpBrowser has been replaced by the Documentation Center, which is also availabel via the Help menu.
After installing add-ons, FrontEndVision and MathVisionTools in particular, you can find the additional documentation about these add-ons also in the HelpBrowser under 'Addons & Links'. In Mathematica 6 you have to follow the link 'Installed Add-Ons' at the bottom right of the Documentation Center home page.