Hi Mahesh,
try sth like this (in Controller):
var oElement = this.getView().byId("uname");
alert("You have entered the Uname"+ oElement.getValue());
When you have a look at the DOM tree, you'll see that the id of an Element is a composition of the name of the view and the id you've given the element.
So if you try to do it with document.getElementById(...) the id hast to be: viewName + "--" + id
Hope that helps!