[Tex/LaTex] create a merged multi column header

Question

This is the image of table.
Can anyone help me create a multi column header ?

Answer 1

something like this:

\documentclass{article}
\usepackage{multicol}
\usepackage{colortbl}
\usepackage{xcolor}
\begin{document}
\begin{tabular}{|l|l|l|l|l|l|}
\hline
\rowcolor{blue!20}Utente & \multicolumn{2}{l|}{Parte pubblica} & \multicolumn{3}{l|}{Parte segreta}\\\hline
Aldo & N & e &p,q [N=p*q] & b = $\Phi$(N) & d\\\hline
Esempio& 55 & 3 & 5, 11 [55= 5*11] & 40 = $\Phi$(55) & 227\\\hline
\end{tabular}
\end{document}