The neatest way to achieve what you want to do is probably to create an class representing the code that exposes the digits via properties that are bound to the textboxes (or as a string via one property and then use a ValueConverter to update the appropriate digits) and implements the INotifyPropertyChanged interface (throwing a PropertyChanged event each time the property/properties are set. You can then either create a handler that listens for PropertyChanged events from the code object, checks that all of the digits are filled in and if so loads the data from XML, or alternatively you could do that checking inside the object and raise some other event to let the application know a full code is entered.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.