\documentclass%:default:classopt:[%{beamer}

%:default:pkgs:%

%\usetheme{Malmoe}
\usetheme{AnnArbor}
%\usecolortheme{seahorse}
%\usecolortheme{rose}
%\usecolortheme{orchid}

% You must set \author before \begin{document}, because beamer uses it to set
% the author field in PDF, which fails if \author is set after \begin{document}.
% But pay attention, babel is not active here so "o (and the like) do not work.
\author{your name}

\begin{document}

\title{The title of your presentation}
\subtitle{Maybe, a subtitle}
\date{1970-01-01}

\begin{frame}
  \titlepage
\end{frame}

\begin{frame}
  \tableofcontents
\end{frame}

\section{A proof}

\begin{frame}
  \frametitle{There Is No Largest Prime Number}
  \framesubtitle{The proof uses \textit{reductio ad absurdum}.}
  \begin{theorem}
    There is no largest prime number.
  \end{theorem}
  \begin{proof}
    \begin{enumerate}
    \item<1-| alert@1> Suppose $p$ were the largest prime number.
    \item<2-> Let $q$ be the product of the first $p$ numbers.
    \item<3-> Then $q+1$ is not divisible by any of them.
    \item<1-> Thus $q+1$ is also prime and greater than $p$.\qedhere
    \end{enumerate}
  \end{proof}
\end{frame}

\end{document}