In order to use recapcha2 you need to get a site key and secret from google, luckily you can get them in less than 2 minutes and for free!
These are the steps to get them:
1.-Go to https://www.google.com/recaptcha/admin, since recapcha2 was done by google you will need a gmail account to get your keys.
2. – Put whatever you want in the first box (1) and your domain name in the second box (2), then click the register button (3). (Sorry for the Spanish screenshots, google didn’t want to show the English version =( .)
3. – After hitting register google will redirect you to a page where you can see your site key and secret
4.- Lastly use those keys to configure your recaptcha field
5. – That’s it =).