\documentclass[12pt]{article}
\usepackage[utf8]{inputenc}
\usepackage[greek,english]{babel}
\usepackage{alphabeta}
\author {Arsenis Chrysikopoulos}
\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
      formating its output , and is itself written in the Tex macro refers to the encoding or tagging conventions tha are used in LaTex documents. "
\end{center}
 Εδώ γράφω Ελληνικά 
\end{document}      
