If you have a Users as response or a Array/JSON you defined, First You need to set the selected value in controller, then you put the same model name in html. This example i wrote to explain in easiest way.
Simple example
Inside Controller:
$scope.Users = ["Suresh","Mahesh","Ramesh"];
$scope.selectedUser = $scope.Users[0];
Your HTML
<select data-ng-options="usr for usr in Users" data-ng-model="selectedUser">
</select>
complex example
Inside Controller:
$scope.JSON = {
"ResponseObject":
[{
"Name": "Suresh",
"userID": 1
},
{
"Name": "Mahesh",
"userID": 2
}]
};
$scope.selectedUser = $scope.JSON.ResponseObject[0];
Your HTML
<select data-ng-options="usr.Name for usr in JSON.ResponseObject" data-ng-model="selectedUser"></select>
<h3>You selected: {{selectedUser.Name}}</h3>