\section{First Section of first chapter}
\subsection{Let's talk about A}

I must quote \citet{FavoriteAuthor} because they did a great job.

\subsection{And now B}

...

\section{But what about this}

\begin{figure}[ht]
    \centering
    \includegraphics[]{example-image-a}
    \caption{Image A.}
\end{figure}

\begin{figure}[ht]
    \centering
    \includegraphics[]{example-image-b}
    \caption{Image B.}
\end{figure}