# How can I draw in SE? [duplicate]

I don't know how to draw a picture here: in SE. I have seen that people paste in the end of the code something similar to [1] http://...... Can you help me? For example I let here a code of a picture, that it's correct in tex, but it doesn't draw anything here:

\begin{center}
\begin{tikzpicture}
\draw[->]       (- 4, 0) -- (4,0) node[below left] {$x$};
\draw[-]       (-0.1,1) -- (0.1,1);
\draw[-]       (0,-1) -- (0,1) node[left] {$1$};
\draw[-]       (-0.1,3) -- (0.1,3);
\draw[-]       (0,0) -- (0,3) node[left] {$3$};
\draw[->]       (0,-1.1) -- (0,4) node[below left] {$({\chi}_{[- 1 , 1]} * {\chi}_{[- 2 , 2]})(x)$};

\foreach \i in {-3,...,3}
{
\draw (\i,0) -- + (0,-0.1) node[below,font=\scriptsize,fill=white] {\i};
}
\draw[red,     samples=1000, domain=-4:-3] plot(\x, 0);
\draw[red,     samples=1000, domain=-3:-1] plot(\x, 3+\x);
\draw[red,     samples=1000, domain=-1:1] plot(\x, 2);
\draw[red,     samples=1000, domain=1:3] plot(\x, 3-\x);
\draw[red,     samples=1000, domain=3:4] plot(\x, 0);
\end{tikzpicture}
\end{center}

• there is no online image generation mechanism on this site just take an image locally and upload in the editor, but the question should be asked in meta it is off topic here. – David Carlisle Jan 28 '17 at 20:14
• Luck on your vote and thanks to everyone. – joseabp91 Jan 28 '17 at 20:24