Ah, AppleScript is a FABULOUS thing ... but the documentation is sketchy and fragmented IMHO. To start with, here are some ESSENTIAL web sites:
http://www.apple.com/applescript/ http://bbs.applescript.net/ http://www.applescriptsourcebook.com/ http://www.applescripter.com/
If you're running OS8/9 look on your OS CD for the AppleScript folder to install the lite version of the OSA menu for easy access to Finder/Folder scripts.
Starting out, you can also open up the "Script Editor" in your AppleScript folder and "record" simple Finder actions to see how the syntax of AppleScript really works.
For many of the application specific scripts, you can drag the script on top of the ScriptEditor icon and edit parameters of the script to suit your liking (the Netscape scripts just target "window1" if memory serves).
To learn what commands and syntax applies to a particular application (and to see if it's scriptable at all) just drag and drop the application itself onto the script editor and a "Dictionary" for that particular app will appear. This also works with "Control Panels" since they are often really applications. From this Dictionary, you can begin to craft scripts for particular apps.
AppleScript is an incredible resource. Just start slow and try not to get frustrated!!