Step 1 : Login in to your facebook account.
Step 2 : Goto your page.
Step 3 : Click on Update Information from edit page.
Step 4 : Select Resource from left side then click on use social plugin.
Step 5 : Now Click on Like Button.
Step 6 : Now Enter your facebook page link in first text box then click on Get code button.
Step 7 : Click on XFBML and copy those codes.
Step 8 : Goto your Blogger and select your blog.
Step 9 : Click on Layout and then Click on Add Gadget.
Step 10 : Search for HTML/JavaScript.
Step 11 : Click on Plus Button. Then paste those Code in Content box then click on Save.
That It...!!! you will see your fanpage gadget on your Blog.