I see nothing under the link you posted. Player_walk is an example in the manual, its not an action from the tutorial. The tutorial is under the "Tutorial" link here, its also on the download page for download.

There are predefined actions, they are called "Templates". There is a tutorial series in the AUM magazine about them, but before using them you should first learn how Gamestudio is organized and how to write a script, this is highly recommended. This is where you should start. Everything else comes later.