In a nutshell, once you add a single line of code to your blog and when readers hover their mouse on the images within your blog (both new and existing images), small Pinterest buttons will appear on them. If your images are attractive enough, then they will be shared on Pinterest along with a backlink to original article and it will get you a boost in traffic from Pinterest.
Whenever your readers Pin your images to their boards then the images will be shared with their followers.
Pinterest ranks among the top 50 websites on the Internet getting around 500-800 Million page-views per month. Simply put, you cannot ignore Pinterest as a potential source of web traffic. Beautify your posts with attractive images, add the code mentioned in this tutorial to make the images shareable and expect a huge bump in the traffic.
You can make the images shareable by adding a single line of code from Shareaholic. Create an account at Shreaholic and add your website to the account (under "My Sites"). Now from the settings screen, deactivate all the options except "Shareable Images" (if you are planning to add other features of Shareaholic like floating share widget etc. then keep those options active as well).
The code from Shareaholic looks somewhat like this
Paste that code in your blog's template
Under Blogger/ your blog -> Template -> Edit HTML, find this code in the template:
Paste the code from Shareaholic immediately above it and let your readers share your images!