This package allows you to customize headers and footers in the LaTeX document.
You can find comprehensive information on this package in The LaTeX Companion.
Here I’ll explain how to make a simple header showing your name and the date.
This is what you need to include:
\documentclass{article}
\usepackage{fancyhdr}
\pagestyle{fancyplain}
\begin{document}
\lhead{John E. Smith}
\rhead{\today}
Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Quisque ut ante pulvinar mauris interdum euismod. Aliquam dui tellus, blandit at, tincidunt ac, feugiat id, nibh.
Phasellus id metus. Aliquam erat volutpat. Donec fringilla. Donec euismod, velit quis adipiscing hendrerit, enim eros tempor mi, a hendrerit ipsum eros eget leo.
\end{document}
Here is the output PDF of the document: SimpleFancyhdr.pdf
The fancyhdr package was created by Piet van Oostrum.
Useful Links
- fancyhdr user’s manual – http://www.ctan.org/tex-archive/macros/latex/contrib/fancyhdr/fancyhdr.pdf
LaTeX for Humans 
Nice intro, how can you change the line thickness and margins?
how can i write authers name in one page and title of paper in other page in 1st line of page