documentclass[12pt]{article}

usepackage{a4wide,german,fancyhdr}
usepackage[T1]{fontenc}
usepackage[utf8]{inputenc}
usepackage{graphicx}
usepackage{epstopdf}

begin{document}

text before

begin{figure}[h!]
  centering
  %includegraphics[width=0.5textwidth]{path2/figure.png}
  caption{first line\hspace{textwidth} Second line.}
end{figure}

text after

end{document}