It is always convenient and helpful to have a (clickable) TOC while we are preparing for our publications. It will give us a big picture of our work.
Put the piece of code I provided below immediately before your \section{Introduction} in your .tex file, you will have a clickable TOC in your tex created pdf! Happy Writing:)!
\newpage
\thispagestyle{empty}
\setcounter{tocdepth}{4}
\normalsize
\tableofcontents
\normalsize
\newpage
%\pagestyle{fancy}
\setcounter{page}{1}
\setcounter{section}{0}
%\cfoot{\small \sffamily \thepage}
\pagenumbering{arabic}