I want to create an automatic pop up window on my website. What code should I use to not only pop up the page automatically, but not 'reopen it' if the pop up is still open when revisiting the page that previously opened it.

I'm not too knowledgeable with HTML code, so an example would be great. What I have working right now opens the pop up automatically, but if possible I don't want the website to regenerate the pop up if the pop up is still open on someones computer when revisiting the page that opened the pop up.
crsimon, actually in this situation the pop up would make my website better. Yes I know this is rare for a pop up

I look at links, that's where I found the code initially, but I could not find away to make the pop up to stop regenerating its self.
Ron, not to be a jerk but it seems like you did not read my question or take it seriously, as none of those links did what I wanted. I could of easily googled that myself. That's not what I'm asking for here.