This tutorial will teach you how to add social media sharing button (Facebook, Twitter, Google +1 (plus one), LinkedIn) widget on your Blogger or BlogSpot blog.
Demo : See the left side of your browser..
Social media share buttons are everywhere. They are very popular because webmasters and bloggers get more traffic from Social Network sites through it. Share buttons like Facebook Share, Facebook Like, Facebook Recommend, Twitter Tweet, Google +1 button, StumbleUpon, Tumblr button, Digg This, and LinkedIn Share boost traffic back to your website. They make it easier for visitors and readers to share your content to their friends and connections.
"share buttons" widget is very easy to install to your blog. All you need to do is edit two parts of your Blogger template (the main code and the page elements).
For this tutorial, we have gathered four most popular share buttons today: Facebook Like, Twitter Tweet, Google +1 (plus one) button, and LinkedIn Share. They are all in vertical count (or tall) format and will show up on the left side of your blog.
Below are the steps on how to add floating Facebook Like, Twitter Tweet, Google +1 (plus one) button and LinkedIn Share buttons to the left hand side of Blogger or BlogSpot blog.
1. Log in to your Blogger account.
2. Click Design.
3. Click Edit HTML.
4. Look for HEAD tags
5. Copy this code:
6. Place it below HEAD tags
7. Click the Save Template button.
8. Click Page Elements, located before Edit HTML.
9. Click Add a Gadget on the sidebar or any Add a Gadget you see on your page elements.
10. A new window will show up. Scroll down and look for HTML/JavaScript in the selection.
11. Click on the button with a plus (+) sign next to HTML/JavaScript.
12.copy this code and paste to it
Source : http://www.howbler.com/2011/06/blogger-widget-add-floating-social.html#white