Insert author and image description.Latex

You can use the package caption and then use \caption{} as many times as you want. To determine the position of the caption will follow the order in which you write the code. So for one caption above and one below:

\caption{}
\includegraphics{}
\caption*{}

Detail that in the second \caption{} I added a * not to number the legend.

Example :

\documentclass{article}
\usepackage[brazilian]{babel}
\usepackage[utf8]{inputenc}
\usepackage[demo]{graphicx}
% pacotes para legenda
\usepackage{caption}

\begin{document}

\begin{figure}
\centering
\caption{Taxonomia de Jogos Sérios}
  \centering
  \includegraphics[width=.4\linewidth]{image1}
\caption*{Fonte: Laamarti, Eid e El Saddik (2014, tradução nossa)}
\label{fig:test}
\end{figure}

\end{document}

In addition to the elegant @Willian solution, I would remind you that it is possible to write LaTeX in of the environment, with the content you want ...

\documentclass{article}
\usepackage[brazilian]{babel}
\usepackage[utf8]{inputenc}
\usepackage[demo]{graphicx}

\begin{document}

\begin{figure}
\centering
\caption{Taxonomia de Jogos Sérios}
  \centering
  \includegraphics[width=.4\linewidth]{image1}\
 Fonte: Laamarti, Eid e El Saddik (2014, tradução nossa)
\label{fig:test}
\end{figure}

\end{document}