The main option is once that a member has clicked on a banner a new window will have to open, there you will have to frames: one with countdown and the second with the advertiser site.
Now if you want to refresh the main page (where the banners are displayed) when the countdown ends and the user has been credited is easy, i will give you just a point: think that the page opened when the user click on a banner is a child for the main page.
If you will not deal send me a PM but at least try to resolve it alone, you will learn something

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