Best Practice Question for passing XML info between classes

Let me start off by apologizing for my limited OOP experience. I realize I have probably made more than one error in my thought process here. I am hoping someone can help straighten me out.

I am creating an app in Flash Pro using AS3 for my wife to track our son’s hockey progress. The app will have three sections: start, data entry, data retrieval. I have created the screens as separate classes to handle their individual functions. My data is stored in XML that I need to pass between these screens. I tried creating a separate class to handle my XML, but I am having trouble reading and writing to the new class. Is there a better way to handle passing this XML information around inside my application? Eventually I would like to have the app write to an external XML file then pull the new rewritten file back in. This code is in one of the .as files already, it’s just not working yet.

I added my files below (7 as and 1 fla Zipped) if you want to check them out. Sorry for the poor programming and the sad design. The app is still gestating.

Any help someone can offer will be greatly appreciated.