Short tutorial on Expressions
I have created a small tutorial (with examples) on Expressions, which is a great starting point if you want to learn more about them:
Slideshow on Expressions
http://tinyurl.com/course2pdf (81 KB)
Slideshow on Expressions with examples
http://tinyurl.com/course2zip (2.3 MB)
And of course if you have questions, you can post them here in the forum.