Need help with new reCaptcha

I'm trying to stop spamming on my web, so I decide to put this recaptcha, but... Need help on configuring it on php, I use a form that calls a php file that creates a new class.phpmailer and send the email and stores the info into a Database, so my form action call a sendform.php file, where do Icheck if the user has fill correctly the captcha? And the other issue, cant change the size of the widget, my form width is 200px and can't find how to make the recaptcha fit into it. Thanks for any help -- You received this message because you are subscribed to the Google Groups "reCAPTCHA" group. To unsubscribe from this group and stop receiving emails from it, send an email to recaptcha+unsubscribe@googlegroups.com. To post to this group, send email to recaptcha@googlegroups.com. Visit this group at http://bit.ly/1dkFnYd. For more options, visit http://bit.ly/P65DvS.