Code:
$this->_request->getParam('PARAM NAME HERE')
comes from url
Code:
http://localhost/<controller>/<action>/param/value/param2/value2/etc...
localhost can be anything really (wherever it's being hosted).
I don't see why there's a param in the index.phtml. Or why there should be one. But you can always concider linking to
Code:
http://localhost/<controller>/index
instead of
Code:
http://localhost/<controller>