If you haven't had a chance to study and understand the docs yet, these examples can look relatively advanced.
Simpler examples can be found in the documentation for individual action commands.
For a full tutorial, start from the main Selectors section and work forward. By doing this you will understand all the syntax you need to be able to code with Active CSS.
You can get pretty complex with Active CSS, just like you can with CSS. You can do things in different ways, and the examples in this section have been written to demonstrate and test different techniques. So when you look at the clock examples below, realise that there could actually be a simpler way to get the same result in Active CSS.
All individual Active CSS commands are inherently simple one-liners. How you combine them to produce amazing things is not only a matter of skill, but also what style you are familiar with coding in and also a matter of personal taste. There is no right way to code in Active CSS, basically. Find a way that works intuitively for you.
Enjoy the examples!