For a large document, it is a kindness to your reader to provide a
Table of Contents. If you have been using \section commands
throughout your document, then LaTeX has all the information
that it needs to construct one for you. Place the command
\tableofcontents after your \begin{document} command.
It may be necessary to run LaTeX twice on a document with a Table of Contents: the first time, LaTeX stores the page numbers for the sections in a separate file, and then the second time LaTeX writes this information into the Table of Contents. If you have question marks instead of page numbers in your Table of Contents, run LaTeX again.
Practice:
Create a three page document with at least ten sections and a Table of Contents.