Congratulations! You've been gifted a membership for a year from another member.
The email you've been sent contains a link which you can use to take up the membership. Click the link, or copy it into your browser's address bar, and you'll be taken to the membership confirmation page. That's it - you have had a year's paid membership added to your account.
You don't need to take up the membership if you don't wish to, but we hope you do. If you don't wish to take it up, simply ignore the email you were sent and that will be it.