How can I pass variables from options to my controller?

Can someone tell me how to collect the values? Please select on.change in the drop down box and use the value as a variable in the controller. For some reason the $ColorPicked variable won't be in $scope.base=response.data.type. $ColorPicked is rotated; however, if I just delete $ColorPicked and enter Red, it works fine.

I'm pretty new to Angular and JS, so please excuse my stupidity. I've googled and googled for a definitive answer, but I've found nothing.

INDEX.HTML
<h3>Color:</h3>
<select class="formBoxes" id="ColorPicked">
<option value="Red">Redd</option>
<option value="Blue">Blue</option>
<option value="Green">Green</option>
</select>

SCRIPT.JS
$ColorPicked = "Red";

var app = angular.module("computer",['ngRoute'])
.config(['$routeProvider', function($routeProvider){
  $routeProvider.
    when('/main',{
       templateUrl: 'archetype.html',
      controller:'MainCtrl'
    }).
    otherwise({redirectTo:'/main'})
}])

.controller('MainCtrl', ['$scope', '$http', function($scope, $http){
  $http.get('archetype.json').then(function(response){

    $scope.base = response.data.type.$ColorPicked;

    ;
  });
}]);