Middle-man page for Wordpress posts?

How can I make a page come up when a user clicks through to a post on my Wordpress site? I essentially need to make a middle-man page come up where a person will be asked to fill out their email before proceeding to the post they were requesting. I know how to do everything else except I don't know how to insert this page so it comes up before the post that they were trying to access.

I have a large website where I am trying to implement this strategy but my programming knowledge is minimal. Help is greatly appreciated from those of you more knowledgeable in this area.

Thanks for your time.

hey its called a 'content locker' search for 'wordpress content locker' or something.

It's called a WordPress "hook". Look it up.