How do I set a cookie?

Hello,

I am not sure if I am posting to the correct forum or not...Here is what I am
trying to do..Maybe you can lead me in the right direction...

When a person visits a page on my site, I would like to have a page with a
form on asking him to register before moving on...After registering via a form,
it will forward them to the intended destination page...It will also set a
cookie on their computer that they have registered...The next time the visitor
visits the page the registration form does not come up...It just forwards them
to the intended destination page...

I also thought about doing this with a popup...When a visitor visits a
particular page a popup will show up asking them to register...After they
register, the popup will close and never ask them to register again based on a
cookie that was set on their computer...If the visitor does not register, it
will continue to popup on each visit...

Any ideas would be very helpful...

Regards,
Mike