\documentclass{myclass}

\thispagestyle{empty}

\usepackage{tikz}

\begin{document}

\begin{tikzpicture}
\foreach \x in {-4,-3,...,4} {
\foreach \y in {-8,-7,...,8} {
\shade[ball color=black!10!white] (\x,\y) circle (.2);
}
}
\draw[ultra thick] (-4,0) -- (4,0);
\draw[ultra thick] (0,-8) -- (0,8);
\draw[ultra thick, red] (-4,-8) -- (4,8);
\draw[ultra thick, blue] (2,0) -- (2,4) -- (0,4);
\draw[ultra thick, green, dashed] (0,7) -- (3.5,7) -- (3.5,0);
\foreach \x in {-4,-3,...,4} {
\shade[ball color=red] (\x,2*\x) circle (.2);
\shade[ball color=blue] (\x,0) circle (.2);
}
\foreach \y in {-4,-3,...,3} {
\shade[ball color=blue] (0,2*\y) circle (.2);
\shade[ball color=green] (0,2*\y+1) circle (.2);
}
\shade[ball color=blue] (0,8) circle (.2);
\end{tikzpicture}
\end{document}