How to add a facebook like button in a Confluence page?

1. You should create the code from the facebook developers' page for the page that you want to like.

          http://developers.facebook.com/docs/reference/plugins/like/

2. Copy the generated code.
3. Create a confluence page or open editing for an existing one. Add a html-include macro.
4. Paste the copied code into it, and save the page.

5. Here it is!

Similiarly, you can add twitter follow button.

https://twitter.com/about/resources/buttons