Latex Tikz drawing

I am trying to draw following diagram on a latex using Tikz library but unfortunately the nodes are unable to be moved around. Its always centered on the center and cannot be moved. Can anyone help me how to draw this diagram on a latex.

\begin{figure*}[t!] %  figure placement: here, top, bottom, or page
\centering
\includegraphics[width=7.2in]{../picture/sequence2}

\begin{picture}(0,0)
%\put(188,124){\vector(0,-4){30}}
%\put(118,124){\vector(0,-4){30}}
%\put(48,124){\vector(0,-4){30}}
%\put(-22,124){\vector(0,-4){30}}
%\put(-93,124){\vector(0,-4){30}}
%\put(-155,124){\vector(0,-4){30}}
%\put(-225,124){\vector(0,-4){30}}

\put(95,117){\small Boundary Estimation}
\put(107, 74){\small Modeling and }
\put(116, 65){\small Learning}

\put(8, 74){\small Tracking and }
\put(8, 65){\small Segmentation}

\end{picture}

% \begin{tikzpicture}[node distance = 2cm, auto]
% \node at (-10,01) [mynode] (n0){Boundary Estimation};
% \node [mynode, below of = n0 ] (n1){Modeling and Learning};
%
% \node [mynode, left of = n1, distance = 3cm ] (n2){Tracking and Segmentation};
%
%
% \end{tikzpicture}

\caption{example caption}
\label{fig:example}
\end{figure*}

-
Please make your code compilable (if possible), or at least complete it with \documentclass{...}, the required \usepackage's, \begin{document}, and \end{document}. That may seem tedious to you, but think of the extra work it represents for TeX.SX users willing to give you a hand. Help them help you: remove that one hurdle between you and a solution to your problem. –  Jubobs Jun 25 at 16:47
Why is this tagged tikz-pgf? –  cfr Jun 26 at 2:05
Are you trying to overlay the pict2e picture on top of the graphics image? If so, you will need \raaisebox. –  John Kormylo Jun 26 at 4:25