Facebook`s new Open Graph API lets users to add their like button on their website pages. Facebook has their detailed documentation to help you for implementing the “Like” buttons onto your own website or blog, it’s easier on some other platforms like WordPress.
There are dozens of Facebook Like plugins for WordPress available in the official WordPress.org Plugin Repository. These solutions are the easiest way to add a “Like” button to your site, but they don`t provide you a full control for customizing that button like you want so you can get this by just inserting a few lines of code into your theme files.
Open your single.php file in your wordpress theme, and in the post loop, add the following line wherever you want the button to appear:
You can adjust the parameters like show_face=true or false and colorscheme=dark or light to make it like your website lookings.
You can see the official Facebook documentation or the two tutorials above for more detailed information.