how to use subfigure feature in Latex

In order to use subfigure feature in Latex:

\documentclass{article}

\usepackage[pdftex]{graphicx}

\usepackage{subfigure}




To reference subfigure do Figure ~\ref{fig:second}




\begin{figure} [htp]

   \begin{center}

    \subfigure[My First Figure]{\label{fig:first}\includegraphics[scale=0.30]{first.PNG}}

    \subfigure[My Second Figure]{\label{fig:second}\includegraphics[scale=0.30]{second.PNG}} \\

  \end{center}

  \caption{MAVIS Interfaces}

  \label{fig:edge}

\end{figure}

the solution is from http://www.andy-roberts.net/writing/latex/floats_figures_captions