WordPress is such an advanced and smart blog that you need not to do any changes in html codes like in blogger. It enables you to do this automatically using widgets feature. Here is the procedure
First of all login to your wordpress account.
Got to dashboard
On the left side, select appearance>>widgets.
Here locate facebook like widget.
Now on the right side is sidebar.
Select and Drag the facebook like widget on to the sidebar
Write the tittle of fb like box
Add your facebook page url to it.
Click save. Check out your blog, now you have one. WordPress is such an awesome blog and I love it