Text Formatting ⇒ A problem using \cite{}

[HyperComposition]

Hello. I am fairly new to using LaTeX.
Using TeXnicCenter, the citations appear as question marks within brackets (i.e. [?]) in the PDF. I am using commands of the form \cite{2} for a bibliography item such as \bibitem{2}. In the TeXnicCenter output, there are warnings such as "LaTeX Warning: Citation '2' on page 2 undefined on input line 22".
Any help would be much appreciated. I have no idea what I'm doing incorrectly. I am currently using the following packages:

\usepackage[usenames]{color}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage[colorlinks=true,linkcolor=webgreen,filecolor=webbrown,citecolor=webgreen]{hyperref}
\definecolor{webgreen}{rgb}{0,.5,0}
\definecolor{webbrown}{rgb}{.6,0,0}
\usepackage{fullpage}
\usepackage{graphicx}
\usepackage{amscd}
\usepackage{color}
\usepackage{float}
\usepackage{graphics,amsmath,amssymb}
\usepackage{amsthm}
\usepackage{amsfonts}
\usepackage{latexsym}
\usepackage{epsf}

Thank you.

[frabjous]

Keep in mind that you need to process twice in order for references to be sorted out. It's perfectly normal to get ?'s the first time processing a file.

If it's not that, then try posting a complete minimal working example, following instructions at the link I just gave. Remove all packages not necessary for generating the problem, but retain a complete document that can be processed as is.

I don't think this is the cause of your problems, but people don't usually use numbers for their citation keys, but something describe to help them remember, e.g. \cite{miller2008} and \bibitem{miller2008}. They'll still turn up as numbers in the output, assuming you're using a numbered style.