1.Go to Dashboard >> Layout>> Edit HTMl
Copy the whole html code and paste it into the Notepad.
2. Search the word post-header-line or post-header-line-1 or <data:post.body/>
3. Copy the following code and paste below the post-header-line or post-header-line-1 if you got both.
<b:if cond='data:blog.pageType == "item"'>
<style>.fullpost{display:inline;}</style>
<p><data:post.body/></p>
<b:else/>
<style>.fullpost{display:none;}</style>
If you don't have line post-header-line or post-header-line-1 by default just make sure that the code placed above the line <data:post.body/>
4. Add another code below the line <data:post.body/>
<b:if cond='data:blog.pageType != "item"'><br />
<a expr:href='data:post.url'>Read more...</a>
</b:if>
</b:if>
5. Make sure you edited the code as below.

Save the template.
6. Goto Settings >> Formatting
Enter the Post Template box as below
<span class="fullpost">
</span>
Save the settings.
7. Create the new post as below.

8. You will get the published post with this option.



