I want to fill a ring like this picture
With Geogebra, I tried it by plot 4<=x^2+y^2<=9
and this is the code in Geogebra
\documentclass[12pt]{standalone}
\usepackage{pgf,tikz}
\usetikzlibrary{arrows}
\usetikzlibrary{patterns}
\pagestyle{empty}
\begin{document}
\begin{tikzpicture}[line cap=round,line join=round,>=triangle 45,x=1.0cm,y=1.0cm]
\clip(-3.3,-3.3) rectangle (3.3,3.3);
\draw [rotate around={0.:(0.,0.)},color=black] (0.,0.) ellipse (2.cm and 2.cm);
\draw [rotate around={0.:(0.,0.)},color=black,fill=black,fill opacity=0.1] (0.,0.) ellipse (3.cm and 3.cm);
\end{tikzpicture}
\end{document}
but, I got
How can I fill the ring as the firt picture?