problem in connecting

Here is a simple example of connectivity :

Note : Make the tables in SQL Server Management Studio.

protected void btnsubmit_Click(object sender, EventArgs e)
    {
           SqlConnection CON;
           SqlCommand COM;
       CON = new SqlConnection(ConfigurationManager.ConnectionStrings["Database_Name"].ConnectionString);
      COM = new SqlCommand("INSERT INTO TableName (ID, Name, Address) VALUES (@ID, @Name, @Address)", CON);
            COM.Parameters.Add("@ID", System.Data.SqlDbType.NChar,10);
            COM.Parameters["@ID"].Value = txtid.Text;
            COM.Parameters.Add("@Name", System.Data.SqlDbType.NChar,50);
            COM.Parameters["@Name"].Value = txtname.Text;
            COM.Parameters.Add("@Address", System.Data.SqlDbType.NChar,100);        
            COM.Parameters["@Address"].Value = txtaddress.Text;       
            CON.Open();    
        COM.ExecuteNonQuery();
        Response.Redirect("Default.aspx");       
        //CON.Close();

    }
    protected void btnupdate_Click(object sender, EventArgs e)
    {
          SqlConnection CON;
           SqlCommand COM;
       CON = new SqlConnection(ConfigurationManager.ConnectionStrings["Database_Name"].ConnectionString);
      //COM = new SqlCommand("update TableName set id='"+txtid.Text+"',Name='"+txtname.Text+"',Address='"+txtaddress.Text+"'");
       COM = new SqlCommand("Update <b>TableName</b>set Name=@Name,Address=@Address where ID=@Id",CON);
       COM.Parameters.Add("@ID", System.Data.SqlDbType.NChar, 10);
       COM.Parameters["@ID"].Value = txtid.Text;
       COM.Parameters.Add("@Name", System.Data.SqlDbType.NChar, 50);
       COM.Parameters["@Name"].Value = txtname.Text;
       COM.Parameters.Add("@Address", System.Data.SqlDbType.NChar, 100);
       COM.Parameters["@Address"].Value = txtaddress.Text;
       CON.Open();
       COM.ExecuteNonQuery();
       Response.Redirect("Default.aspx");
       CON.Close();
        
      }
    protected void btndelete_Click(object sender, EventArgs e)
    {
        SqlConnection CON;
        SqlCommand COM;
        CON = new SqlConnection(ConfigurationManager.ConnectionStrings["DataBaseName"].ConnectionString);
        COM = new SqlCommand("Delete from TableName where ID=@ID",CON);
        COM.Parameters.Add("@ID", System.Data.SqlDbType.NChar, 10);
        COM.Parameters["@ID"].Value = txtid.Text;
        COM.Parameters.Add("@Name", System.Data.SqlDbType.NChar, 50);
        COM.Parameters["@Name"].Value = txtname.Text;
        COM.Parameters.Add("@Address", System.Data.SqlDbType.NChar, 100);
        COM.Parameters["@Address"].Value = txtaddress.Text;
        CON.Open();
        COM.ExecuteNonQuery();
        Response.Redirect("Default.aspx");
        CON.Close();
    }

Add a connection String in Web.Config

<connectionStrings>
        <add name="DataBaseName" connectionString="Server=ADMIN-PC;Database=DataBaseName;Integrated Security=True" providerName="System.Data.SqlClient"/>
    </connectionStrings>

Did you search on the internet? I found a huge number of links that you could start with. Or better start reading a book on ASP.Net DB Connectivity.

Some links that I found -
http://www.w3schools.com/aspnet/aspnet_dbconnection.asp[^]
http://msdn.microsoft.com/en-us/library/ff648340.aspx[^]