Hello daustin100,
I am not sure that you can alter the Contact Form fields directly without modifying its source code (template file). I do know you can add additional text by using blocks but am not sure that adding an additional field would carry over into the email.
There is, however, a module that is very popular called WebForm. This module will allow you to add any fields you need to create a customized contact form. Take note that it does require both Views and cTools (Chaos Tools) in order to use it.
Kindest Regards,
Scott M