\documentclass{book}
\usepackage[utf8]{inputenc}
%
% landscape orientation
%
\usepackage[landscape]{geometry}
\usepackage{multicol}
\usepackage{graphicx}
\usepackage{geometry}
\usepackage{lipsum}
\usepackage{verbatim}
\usepackage{eso-pic}
\usepackage{fancyhdr}
\usepackage{tikz}
\begin{document}
\input{./chap/cover.tex}
%HERE YOU CAN CHANGE THE MARGIN SIZE
\newgeometry{left=3cm,right=3cm,outer=5cm,inner=2.5cm}
%DISTANCE BETWEEN COLUMNS
\setlength\columnsep{30pt}
\begin{multicols}{2}
\input{./chap/introd.tex}
\input{./chap/main.tex}
\end{multicols}
\end{document}
