The Beginner events are meant for (wait for it) beginning scripters. Are you a beginning scripter? Check out the events, and see if they make sense to you. If you feel they do not offer a sufficient challenge, check out the Advanced events. The topics are similar for both beginning and advanced scripters. In some cases, they are essentially the same event with additional requirements.
You are; of course, free to attempt all the events from both the beginning field and the advanced field. You are also free to write the scripts in VBScript and in Windows PowerShell. You can even combine both languages into a single script if you wish. For a real challenge, write a single script that solves all 20 events in both VBScript and Windows PowerShell at the same time. That would be impressive. If you want to get into shape for the Scripting Games, it would be wise to review working with the registry, event logs, environmental variables, WMI information, looping, and much much more.
The Advanced field features events for (wait for it) advanced scripters. So what makes an advanced scripter? This is something that we have struggled with for years. What is an advanced topic, and what is a beginner topic? To some extent, something is advanced to a person if he or she does not know the topic, and something is basic if one already knows it. For example, if you were a math major in college, a question about differential equations would be a basic topic; to a music major, however, such a topic might very well be considered advanced. If you want to be advanced, you should review regular expressions, arrays, handling command-line arguments, developing custom functions, and working with graphical interfaces.