I want to create this: 
But I've come up with this one:
I've searched the internet first but the histograms they were plotting were so much complicated.
\begin{tikzpicture}
\begin{axis}[
symbolic x coords={$0$, $1$, $2$},
xtick=data]
\addplot[ybar,fill=blue] coordinates {
($0$, 0.25
($1$, 0.50)
($2$, 0.25)
};
\end{axis}
\end{tikzpicture}
You easily can draw it like normal rectangles using tikz and fill with north east lines from the patterns library.
\documentclass[border=5pt,tikz]{standalone}
\usetikzlibrary{patterns}
\begin{document}
\begin{tikzpicture}[yscale=4]
\draw (-1.5,0)--(3,0) (-1,0)--(-1,.75);
\draw[pattern=north east lines] (-.5,0) rectangle (.5,.25) (.5,0) rectangle (1.5,.5) (1.5,0) rectangle (2.5,.25);
\foreach \x in {0,1,2}
\draw (\x,0) -- (\x,-1pt) node[below]{\footnotesize\x};
\foreach \y in {0.25,0.50}
\draw (-1,\y) -- ({-1cm-4pt},\y) node[left]{\footnotesize\y};
\end{tikzpicture}
\end{document}
