\documentclass[12pt]{article}
\usepackage[utf8]{inputenc}
\usepackage[greek,english]{babel}
\usepackage{alphabeta}

\author {Theofanis Gerodimos}
\title {My first title}
\begin{document}
\maketitle
\section {My first section}
\par My first paragraph
\subsection {My first subsection}
\begin{center}
``LaTeX is a document preparation system and document 
markup language. LaTeX uses the TeX typesetting program for 
formatting its output, and is itself written in the TeX macro 
language.\\

LaTeX is not the name of a particular editing program, but
refers to the encoding or tagging conventions that are used in 
LaTeX documents.
\end{center}
Εδω γραφω ελληνικά
\end{document}
