\documentclass[letterpaper,11pt]{article}
\usepackage[left=0.9in, right=0.8in]{geometry}
\pagestyle{empty}
\raggedright
\def\bull{\vrule height 0.8ex width .7ex depth -.1ex }

\newcommand{\lineunder}{\vspace*{-8pt} \\ \hspace*{-18pt} \hrulefill \\} %command for the Line to be drawn
\usepackage[usenames,dvipsnames]{color}
\definecolor{mygrey}{gray}{.90}

\newcommand{\headergrey}[1]{%
  \noindent\hspace*{-15pt}%
  \begin{tabular}{p{\dimexpr\linewidth-2\tabcolsep+15pt}}\cellcolor{mygrey}\textsc{#1}\\
  \hline\end{tabular}%
  \par\nobreak}%


\begin{document}
\headergrey{Objective}
    Seeking a Full Time position in the area of Blah blah blah Blah
\end{document}