\documentclass{beamer}
\usetheme{Warsaw}
\usepackage{graphicx}
\begin{document}
\title{Beamer Tutorial}
\institute{University of Ioannina}
\date{\today}
\begin{frame}
\maketitle
\end{frame}

\begin{frame}
\frametitle{Outline}
\tableofcontents[part=1,pausesections]
\begin{enumerate}
\item Intoduction
\end{enumerate}
\end{frame}

\begin{frame}
\frametitle{Introduction}
\part{Introduction}
This is the Introduction frame.
\end{frame}


\begin{frame}
\frametitle{Overlay - example}
\begin{itemize}
\item Item 1
\pause
\item Item 2
\pause
\end{itemize}
\end{frame}

\end{document}
