You must to injectinject your controller into application module.
Give to your app a name:
<html ng-app='myApp'>
Inject controller:
var app = angular.module('myApp', []);
app.controller('SimpleController', function($scope) {
$scope.customers = [
{ name:'John Doe',city : 'Pheonix'},
{ name : 'John Smith',city: 'New York'},
{ name : 'Jane Doe',city : 'San Fransisco'}
];
}