when i want to insert code in c# language txtclass.Text its showing ERROR CS1061

SCREENSHOT OF CODE

Code:

using SchoolManagementSystem.Models;
using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using static SchoolManagementSystem.Models.CommonFn;

namespace SchoolManagementSystem.Admin
{
    public partial class AddClass : System.Web.UI.Page
    {
        commonfnx fn = new commonfnx();
        private object txtClass;

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

        private void GetClass()
        {
            DataTable dt = fn.Fetch("select.Row_NUMBER() over (order by (select 1) as [sr.No],ClassId,ClassName from class");
            GridView1.DataSource = dt;
            GridView1.DataBind();
        }

        protected void btnadd_Click(object sender, EventArgs e)
        {
            try
            {
                DataTable dt = fn.Fetch("select * from Class where ClassName = '"+txtClass.text.Trim()+"'");
                {
                    if (dt.Rows.Count==0)
                    {
                        string query = "Insert into Class values('" + txtClass.Text.Trim() + "')";
                        fn.Query(query);
                        lblMsg.Text = "inserted Successful";
                        lblMsg.CssClass = "alert alert-success";
                        txtClass.Text = string.Empty;
                        GetClass();
                    }
                    else
                    {    
                    }
                }
            }
            catch(Exception ex)
            {
            }
        }
    }
}

I want to solve the CS1061 error.

When I add .text I get this error

'Object' does not contains a defintion for 'Text' and no accessible extension method text accepting a first argument of type 'object' could be found

How to insert the data into the SQL Server database? Please help me out.