<form id="form1" runat="server">
    <div>
        输入要保存的值：<asp:TextBox runat="server" ID="txtSave"/>
      <asp:Button runat="server" Text="保存" ID="btnSave" OnClick="btnSave_Click" />
    </div>
    </form>

protected void btnSave_Click(object sender, EventArgs e)
    {
        string save = Request.Form["txtSave"];//按钮是服务器请求
        Session.Add("Save", save);
        Response.Redirect("SessionGet.aspx");
    }

protected void Page_Load(object sender, EventArgs e)
    {
        var save = Session["Save"];
        Response.Write("保存的值为：" + save + "<br/>");
    }