\documentclass[11pt]{article}


\usepackage{lipsum}



\begin{document}



\section{Introduction to \LaTeX\ }


This is my first \LaTeX\ file. 
Based on D.~Knuth's \TeX, \LaTeX\ is a \hfill wonderful document preparation system developed by L.~Lamport.   
Here I'm using a newcommand for \lx.  

\section{documents}


\end{document}





