Linkwithin button helps the reader to see related posts. To add this to your blog, go to http://linkwithin.com/.. You will come to this page.
Enter your email address, blog address, blogging platform and the number of suggestions you want to the widget to display..click on "Get widget".. this window opens up..
Click on "Install widget"..If you have more than one blog, select the blog where you want this widget to appear and change the title if you want to..
Click on "Add widget". You will get this message..If you wish to you can change the position of the widget..It should start working on your blog.