This is a simple graph that use TeX pgfplots package

A simple graph

\documentclass[]{standalone}
\usepackage{xcolor}
\usepackage{pgfplots}
\begin{document}
\begin{tikzpicture}
\begin{axis}[ytick={0,1,2,3,4,5,6,7,8,9,10},yticklabels={$0$,$1$,$2$,$3$,$4$,$5$,$6$,$7$,$8$,$9$,$10$},ylabel={$KWH$}, xtick={0,1,2,3,4,5,6,7,8,9,10},xticklabels={$0$,$1$,$2$,$3$,$4$,$5$,$6$,$7$,$8$,$9$,$10$},xlabel={$Timer$}]
\addplot[smooth, mark=*] coordinates {(0,0)
(1,6)
(1.5,6)
(2,3)
(3,10)
(4,6)
(5,8)
(6,1)
};

\end{axis}
\end{tikzpicture}
\end{document}