\documentclass{book}
\begin{document}
\part{First Part}
\chapter{First Chapter}
\section{First Section}
\subsection{First Subsection}
\subsubsection{First Subsubsection}
\paragraph{First Paragraph}
\subparagraph{First SubParagraph}
\chapter{Second Chapter}
\section{First Section}
\section{Second Section}
\subsection{First Subsection}
\subsection{Second Subsection}
\subsection{Third Subsection}

\end{document}