The result is reflected in higher traffic to your blog ,which is the ultimate goal.So how to do it ,you should go to this Facebook page
See the picture
Before that ,log in to your page that you made for your blog on Facebook ,copy the URL of your page and enter it into the URL field -Like
Anything below the settings such as widht,layout,text,colors,you can experiment a little with that and see what best fits for you.
At the end ,click the Get Code and you'll get two types of code Iframe and XFBML I have worked with this second
Copy the code ,open your dashboard ,open Template -edit HTML expand widget .
Then find this line in template
and paste your code just after that,save template and that's it