What is the step by step procedure to install recaptcha on my social media site

I need to install the reCaptcha on my website www.africatube.net to stop spamers or machines signing up. I don't know much about computer so what is the step by step procedure to do this. Please list steps from 1 to end. Thank you inadvance -- 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.