How to expire page session if it is idle for 10 minutes

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C#

ASP.NET

if a UserHomepage.aspx page is idle for 10 minutes , i want to redirect that to expired page(expired.aspx)

and then if he click back button user has to logged out then redirect to home page(Home.aspx)

how to do this

this is my code
userHomePage.cs

protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            BindGrid();
        }
    }

    private void BindGrid()
    {
        string username = Session["new"].ToString();
        string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
        using (SqlConnection con = new SqlConnection(constr))
        {
            using (SqlCommand cmd = new SqlCommand())
            {
                cmd.CommandText = "select Id,UserName,DocumentType,FormType,Name,Description from tblFiles where UserName ='" + username + "'";
                cmd.Connection = con;
                con.Open();
                GridView1.DataSource = cmd.ExecuteReader();
                GridView1.DataBind();
                con.Close();
            }
        }
    }