I've found the way to install LinkWithin for your blog.
LinkWithin is the posts appeared at the bottom of your entry
Like this one..
LinkWithin may help to increase your blog traffic by showing
some posts of yours related to current entry.
Now, lets begin!!
01. Go to LinkWithin website >HERE<
02. Fill out your information in the box on your right side
03. Select the width (no. of box you want to use)
04. Click GET WIDGET
05. Make sure you are signed into Blogger or Wordpress
06. Click INSTALL WIDGET
07. Select the blog you want this widget to appear
08. (Optional) Drag and drop the LinkWithin box under BLOG POST box
09. Click SAVE and you are DONE!!
*Tutorial credit to blogspotutorials.blogspot.com