How to display caption at the bottom of a figure

Question

I am not able to show the caption at the bottom of figure. I always get in the middle. I would appreciate your help. Below is the code.

\documentclass[fleqn,12pt,a4paper]{article}
\usepackage{fontspec,xltxtra,xunicode}
\usepackage{fancyhdr}
\pagestyle{fancy}
\usepackage{color}
\usepackage{setspace}
\usepackage{hyperref}
\usepackage{cmll}
\usepackage{tabularx}
\usepackage{pifont}
\usepackage{amstext, amsmath}
\usepackage{enumerate}
\setmainfont[Script=Devanagari]{Sanskrit2003}
%
\begin{document}
\begin{figure}[htb]
\begin{center}
{\setlength{\unitlength}{6mm}
\begin{picture}(13,13)(0,0)
\put(-2,-0.5){\framebox(6,3){ What are Pragruhya}}
\put(8,-4){\framebox(7,3.2){
\shortstack{A monosyllabic \\with the exception of }}}
\put(4,1){\vector(1,2){4}}
\put(8,0){\framebox(7,3){
\shortstack{that come\\ after the of }}}
\put(4,1){\vector(1,1){4}}
\put(8,4){\framebox(7,3){
\shortstack{ or \\are called }}}
\put(4,1){\vector(1,-2){4}}
\put(8,-8){\framebox(7,3){
\shortstack{ A ending in \\are called }}}
\put(4,1){\vector(1,-1){4}}
\put(8,8){\framebox(7,4){
\shortstack{ in when \\followed by the \\word in the }}}
\put(4,1){\vector(1,0){4}}
\end{picture}
}
\end{center}
\caption{Some More Sutras}
\end{figure}
\end{document}

Answer 1

You need to tweak the parameters of the picture environment:

\begin{picture}(13,21)(-2,-8)

I may have gotten it slightly wrong. The first pair is the size of the picture, and the second pair is the coordinates of the bottom left corner. By setting the latter to (0,0) and using negative coordinates, you were drawing outside the box reserved for the picture.