After sharing or like a page on Facebook I want to add userpoints in Drupal 7, how can I do this?
First, you need to have your users login to your site using Facebook API. There are many modules for it, two I know and seen used are:
That's the only real way to know "he" on Facebook is "he" on your site.
Then, Facebook will not push it's data to you. So you have 2 cases:
- Button "like this page on Facebook" on your page - you can detect it being clicked and make a rule for it, as Patrick Kenny told in his comment.
- Like clicked directly on Facebook - now that's hard. It was discussed on stackoverflow with some apparently good results, and there are tutorials avaliable.
Last but not least - you need to make sure you grant this bonus only once. If not, users could fabricate points by simply repeatedly liking-unliking your page.