Website screenshot settings – setting up the API

Hi

I tried setting up the above plugin – it requires Google API settings to be entered. The screenshots seem to be for an older setup of Google and I wasn’t able to follow these instructions exactly as the menu options have all changed.

I’ve done the best I can, but when I view my listing on the site, instead of seeing a screenshot of the website, I see this error
Website Screenshot Error
The referrer null does not match does not match the referrer restrictions configured on your API key. Please use the API Console to update your key restrictions.

Please can someone help me with step-by-step instructions on how to set up the Google API so that I can view the thumbnails instead of the error message.

Thanks