autoincrement number on refresh

I'm trying to make a page where someone can apply for staff on my forum. I have two stages of applying, an application, and if that is accepted, a test. I have already on this page: an iframe of a google form. I want to add something where it shows a counter that assigns a unique ID to each person who visits the page. I have absolutely no idea how to code this. I have tried many auto-increment scripts, but none of them seem to work, and when I want to print the variable, nothing. I hope someone knows how to do this better than me. Thanks, TJDoesCode