Instagram api post

how can i post to instagram api?
I want to make an app like instagram and i can login with instagram api via get.
But when i made a post for relationship status is always 400
here is my post code

 $http.post("https://api.instagram.com/v1/users/(userid/i changed)/relationship?access_token="+token,{'action':'follow'}).success(function (data,status,headers,config) {
                  alert('success');
                }).error(function(data,status){
                    alert(status);
                });