Add Captcha to form

I have a non working Captcha on my current form. I need to you implement a standard Captcha service into my form. Also I need you to make the following fields mandatory in the Form before Send is allowed. - First Name - Last Name - Email (validate its an email address <something>@<someting>.<something> If a entry is missing/wrong: popup message "Last Name cannot be empty" should popup (example) Attatched current non-working form attached. Dev site with current form: [login to view URL]