Captcha example form project with success/failure redirect

This is too simple for you guys out there, but I'm fed up with the error messages I get ... (header already sent etc) I need an example form with a captcha spam protection integrated which redirects to a specific page on successful captcha validation and to another page when the entry is incorrect. The success redirect is to a mail-script which is ready and working already, but I get too much spam as I have not used a captcha so far. Now all I need is a captcha spam protection for my form to work. You will provide an example form with example redirects, I will integrate in my forms myself. So no big thing: it is about an example form with integrated captcha and success/failure redirect. Captcha code I can provide as I purchased one from [login to view URL]