nat@cry on "Use if post has tag auto generate link to page"

Hi

I am trying to create a function where if a post has a certain tag, generate a link to a certain page.

Can anyone help with this please my attempts at creating the PHP are failing.

Also I am guessing that I should be adding this to the single.php for this to work.

Any help would be greatly appreciated, plus you would be helping a charity.

Thanks