Download Post Teaser from wordpress.org Plugin Directory
Extract and upload the entire post-teaser directory as .../wp-content/plugins/post-teaser directory of your WordPress installation. NOTE: The issue with location sensitive installation have since been fix in version 3.11.3. The post-teaser.php file is no longer restricted to the root of the plugins directory .../wp-content/plugins/
Go to the Plugins configuration page in your WordPress admin panel, and enable Post Teaser
Auto installation (2.7.x and above)
Click on the link Plugin Browser/Installer under the “Get More Plugins” section at the bottom of the Plugins page in your WordPress admin panel (Yes, this page is found in your blog’s admin page).
Search for “post teaser” in Term.
Click on the install action on the right side of the table where Post Teaser is listed.
Follow WordPress instruction to complete the installation.
Configuration
Post Teaser does not need to be configured in order to work but some users understandably wish to change settings. That’s easy too — the dead simple configuration page can be found under Settings > Post Teaser (for version before 2.6 Options > Post Teaser) in your WordPress admin panel.
Video
Plugin Not Working?
If any errors or problems with the plug-in then write comments.