\documentclass[12pt]{amsart}
\usepackage{amssymb,amscd,amsthm, verbatim,amsmath,color,fancyhdr, mathrsfs}
\usepackage{graphicx}
\usepackage{turnstile}
\usepackage[colorinlistoftodos]{todonotes}
\def\tequiv{\ensuremath\sdststile{}{}}
\usepackage[letterpaper, left=3.75cm, right=3.75cm, top=2.5cm,
bottom=2.5cm,dvips]{geometry}
\setcounter{section}{1}
\newtheorem{thm}{Theorem}[section]
\newtheorem{prop}[thm]{Proposition}
\newtheorem{lem}[thm]{Lemma}
\newtheorem{rem}[thm]{Remark}
\newtheorem{cor}[thm]{Corollary}
\newtheorem{exr}[thm]{Exercise}
\newtheorem{ex}[thm]{Example}
\newtheorem{defn}[thm]{Definition}
\title{Simple Mathematics Template with To Do Notes}
\author{Your Name}
\date{\today}
\begin{document}
\maketitle
\vskip.5in
\LaTeX \todo{Change this...} \\ \\
Or inline.\\
\todo[inline, color=yellow]{More to add later...}
\begin{thebibliography}{100}
\bibitem{Test} J. Smith, \emph{Test Title}, Test Publisher, New York, 19--.
\end{thebibliography}
\end{document}
