Hi Mohammed,
When you ran the LiveCycle Configuration Manager (LCM) during your installation, did you run a turnkey installation? The screen to install the samples should be the screen right after the configuring the Rights credential.
I usually use the turnkey installation. You will see the steps in the section "Configuring LiveCycle ES using Express Mode" on page 11, step 6 at
http://help.adobe.com/en_US/livecycle/es/installturnkey_jboss.pdf (which is located at a link in the Install tab as provided by Robert).
In your existing installation, you should be able to run the LCM again by running the ConfigurationManager.bat located at C:\Adobe\LiveCycle8\configurationManager\bin.
Hope that helps!
...Gil