XML in XL

i've had this book for a while. and in chapter 17 it talks about XML "smart documents", but i, unfortunately have no knowledge of xml whatsoever. can anyone help me/point me to help with created and XML document that will allow me to learn this?

and also, for some reason, the book mentions that i should have a selection called "XML" in my "Data" tab in my menu on Excel, but i dont' have one. is that an add-in i need or something? i'm running XL 2003, so i should have it, right?

any help is appreciated
stephen