Where can I find a successful Moodle Integration example or see a sample site? If not how to go about doing the integration? Thanks
No such integration exists today so there is no sample. To implement such integration, I would recommend building an extension for CiviCRM that could interface with Moodle's APIs:
You could also consider the opposite, creating a Moodle plugin that would interface with the CiviCRM API:
I worked on some CiviCRM-Moodle integration in 2017 with Monish Deb. The main product of that work is CiviMoodle.
With CiviMoodle, users can be created in Moodle from CiviCRM. It also adds a field on the back end of Civi events with a drop-down of all Moodle courses. If you select one, someone registering in Civi will have their corresponding Moodle user registered for that course.
A second extension was written, to bring grades in Moodle into Civi custom fields. However, this isn't really useful to others except perhaps as an example.