Contact Form 7 is a fantastic WordPress plugin which simplifies the boring task of building forms on your WordPress website.
The out-of-the-box install uses an AJAX form submission. This means that users don’t get redirected to another page on your website following a form submission. Instead they are just shown a thank you message within the same page.
This is ideal for users as it makes it smooth and painless. However, this also means that there is no thankyou.html page where you can add your conversion tracking code for Google Adwords.