TP1_ASP/boutique/session1.aspx.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace boutique
{
    public partial class session1 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }

        protected void ButtonEntrer_Click(object sender, EventArgs e)
        {
            Session["identifiant"] = TextBoxIdentifiant.Text;
            Session["logged"]//j'en suis la
        }
    }
}