what I'm trying to do is add a sign up sheet to my site for people to sign up to volunteer at a event. i need a way for people to select the time that they want to sign up for. i only need two people per time slot and. i don't know how to make something like this for my website

Just use Google Calendar and embed it on your site.

The Mac has some cool calendar features that work like a Vcontacts file that is compatible with Outlook, etc. but it may be above the normal person's scope to make it work. I think that willcode4beer has the quickest and easiest solution.