It is one of the biggest disadvantage of Blogger that it has no category feature.
An category is always advantage to your blog as it attracts user to spend more time on your blog.
I will show you how to create category feature on your blog.

• You must have labeled your post.If you don't know what the heck are labels see the pic:
• Labels help your post search able for search engine.
• You can make categories of these labels.
• Now got to Customize-->Edit HTML
• Make sure that you have a backup of your template code in case of any error.
• Make list of categories unordered or ordered according to your preference.
  Now the write code
• we will create an unordered list here.
  

  <ul>

<li><a href="http://yourpage.blogspot.com/search?label=blogger">blogger</a></li>


<li><a href="http://yourpage.blogspot.com/search?label=blogging">blogging</a></li>

<li><a href="http://yourpage.blogspot.com/search?label=google">google</a></li>

<li><a href="http://yourpage.blogspot.com/search?label=posts">posts</a></li>


<li><a href="http://yourpage.blogspot.com/search?label=test">test</a></li>

<li><a href="http://yourpage.blogspot.com/search?label=writing">writing</a></li>

<ul>


  
  And so forth.

  
  
  When you save your settings, you will now see a list of your labels on your sidebar on your classic template.