Step 1

Sign in to your Blogger account. Scroll to the blog to which you want to add the Facebook Like button in the lists of blogs displayed on the Blogger Dashboard page.
Step 2

Click the “Design” tab under the blog’s title. Click the “Edit HTML” tab in the Design submenu at the top of the Add and Arrange Page Elements page.
Related Reading: How to Get Facebook & Twitter Buttons to Line Up Horizontally on Blogger
Step 3

Go to the “Edit Template” section. Click and enable the “Expand Widget Templates” check box to display your blog template’s complete HTML design code.
Step 4

Find the “<data:post.body/>” HTML code tag in the HTML input box. To save scrolling through hundreds of lines of code, press “F3” on your computer keyboard to open the browser’s page search function. Enter the code tag into the search box to quickly find the correct code.
Step 5

Paste the following Facebook Like button code snippet immediately before the “<data:post.body/>” tag:
<b:if cond='data:blog.pageType != "static_page"'> <iframe allowTransparency='true' expr:src='"http://www.facebook.com/plugins/like.php?href=" + data:post.url + "&amp;send=false&amp;layout=standard&amp;show_faces=false&amp;width=450&amp;action=like&amp;font=arial&amp;colorscheme=light&amp;height=35"' frameborder='0' scrolling='no' style='border:none; overflow:hidden; width:450px; height:35px;'/> </b:if>
Step 6

Scroll to the bottom of the page, and then click “Save Template.” Blogger saves the edited template and adds the Facebook Like button to all blog posts
get more here
http://www.edge.org.ng/2015/02/h.html