Friends!!!!

I have found the answer by my self:

var model = new instance.web.Model("model_name");

Here you can get your model then you can do whatever you want on it such as this example:

instance.oepetstore.HomePage = instance.web.Widget.extend({

start: function() {

var self = this;

var model = new instance.web.Model("message_of_the_day");

model.call("my_method", [], {context: new

instance.web.CompoundContext()}).then(function(result) {

self.$el.append("<div>Hello " + result["hello"] + "</div>");

// will show "Hello world" to the user

});

},

});

Regards.