\documentclass[]{article}
\usepackage{invitation}
\begin{document}
\begin{Front}
\To{Anna, Bernard, Didier, Johanna}
\Date{Next Friday Evening at 8 pm}
\Where{The Web Cafe}
\Why{My first XML baby}
\end{Front}
\begin{Body}
\par  
I would like to invite you all to celebrate 
the birth of \emph{Invitation}, my 
first XML document child. 

\par  
Please do your best to come and join me next Friday 
evening. And, do not forget to bring your friends. 

\par  
I \emph{really} look forward to see you soon! 

\end{Body}
\begin{Back}
\Signature{Michel}
\end{Back}
\end{document}