\documentclass[12pt]{article}
\usepackage[utf8]{inputenc}
\usepackage[greek,english]{babel}
\usepackage{alphabeta}
\author {Athanasios Petgazlis}
\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.\\
Εδω γραφω ελληνικα
\end{center}
\end{document}
