Including Images and Figures

\usepackage{graphicx}
...
\begin{figure}[h]
  \centering
  \includegraphics[width=0.6\textwidth]{diagram.png}
  \caption{A labeled diagram.}
  \label{fig:diagram}
\end{figure}

graphicx (loaded in the preamble) is what makes \includegraphics work at all. The figure environment lets LaTeX float the image to a sensible spot on the page instead of breaking the flow of text exactly where you placed it; [h] hints "here, if there's room."

Why This Matters for Your Exams

\label/\ref (next unit) only work on something inside a figure/equation/section that LaTeX numbers -- get the figure environment right first.