C++ XML file editing

I am a c++ noob who is still learning things like structs and classes. However, I want to write a simple program that makes a small change to an XML file. I've googled the matter a little bit, but didn't seem to find much that helps me in my situation.

I want to write a program that changes a date in an XML file. (the date is there to tell a program when to lock you out because your data is too old)

Can someone explain a little bit the simplest way to do this?

you should look into TinyXML