Step 1
Visit facebook  Developers 

 Step 2
Select Like Button under Social plugins

 Step 3
Past you Website / Blog URL under Get your Like button code

 set the Width, Layout, Action Type as you want

 Step 4
 Click 'Get Cod'

 Step 5
Under HTML/ 5XFBML / IFRAME / URL opposition

  Select  IFRAME and get the cod

 Step 6

 Visit you blog / Website 
Widget -> HTML cod and past it.and you will get the FB like button for you website