\documentclass{article}
\usepackage{gchords}
\thispagestyle{empty}

\begin{document}

\def\numfrets{4}

\chords{
\chord{t}{n,p3,p2,n,p1,n}{C}
\chord{t}{n,n,p2,p2,p1,n}{Am}
\chord{t}{x,n,n,p2,p3,p1}{Dm}
}

\end{document}