Q:

When Assigning different value to a scope and just call one

I'm trying to write for the first time with AngularJS and I'm not a developer at all. 
I'm very beginning at programming. 
Here's my problem;
I want in var ouinon assign to the $scope.colors, the value of the selected color input by the user in front-office. 
Of course putting $scope.colors.name doesn't work... (in console.log, it's "undefined")
It may seem easy to you, but I don't see what I'm doing wrong. 
JS Part:
function LookCtrl($scope, $http){

    $scope.colors = [
        {name:'blue', shade:'femme'},
        {name:'red', shade:'femme'},
        {name:'yellow', shade:'femme'},
        {name:'blue', shade:'homme'},
        {name:'red', shade:'homme'}
    ];

    $scope.myColor = $scope.colors[2];  

    var ouinon = "http://api.shopstyle.fr/api/products?pid=uid7689-25635133-51&cat="
        + $scope.colors.name + "&limit=60&fl=d0&sort=Popular";

    $http.get(ouinon).success(function(data){
        $scope.look = data;
    });

HTML Part:
<section ng-controller="LookCtrl" ng-init="init()" class="panel panel-padding left" 
    ng-class="{center:panel==1, right:panel<1}">
    <h1>Selection: </h1>
    <select ng-model="myColor" 
        ng-options="color.name group by color.shade for color in colors">
    </select>

A:

You're almost there. 
Your $scope. MyColor is bound to the color that is selected. 
You can use $scope.MyColor.name to get the name. 
Also, I think you are writing the controller incorrectly.  It seems that what you are trying to achieve is to make an Ajax call to get some data, but what is the trigger to get the data?  If it is based on when selection changes, then you should write your controller as follows:
.controller("LookCtrl", ["$scope", "$http", function ($scope, $http){

    $scope.colors = [
        {name:'blue', shade:'femme'},
        {name:'red', shade:'femme'},
        {name:'yellow', shade:'femme'},
        {name:'blue', shade:'homme'},
        {name:'red', shade:'homme'}
    ];

    $scope.myColor = $scope.colors[2]; // default selection

    $scope.onChange = function(){
        var ouinon = "http://api.shopstyle.fr/api/products?pid=uid7689-25635133-51&cat="
        + $scope.MyColor.name + "&limit=60&fl=d0&sort=Popular";

        $http.get(ouinon).success(function(data){
           $scope.look = data;
           $scope.$apply(); // this is needed since it's an async call
        }
    };

}]);

Then the HTML:
<section ng-controller="LookCtrl" ng-init="init()" class="panel panel-padding left" 
    ng-class="{center:panel==1, right:panel<1}">
    <h1>Selection: </h1>
    <select ng-model="myColor" ng-change="onChange()"
        ng-options="color.name group by color.shade for color in colors">
    </select>
</section>

