Login Page in WCF

Question

Hi,i am able to get data in grid view from database in WCF but want to create Login Page using WCF. I have searched on google, i am not getting please tell me how to create?I am new in WCF.

i have create service as -

[OperationContract]

    DataSet SelectUserDetails(string userid1, string password1);

public DataSet SelectUserDetails(string userid1, string password1)

    {

        using (SqlConnection con = new SqlConnection(strConnection))

        {

            con.Open();

            SqlCommand cmd = new SqlCommand("SELECT UserId,Password FROM M_Users", con);

            SqlDataAdapter sda = new SqlDataAdapter(cmd);

            DataSet ds = new DataSet();

            sda.Fill(ds);

            cmd.ExecuteNonQuery();

            con.Close();

            return ds;

        }

    }

how to call this and userid and password credentials on button click event???
protected void btnsubmit_Click(object sender, EventArgs e)
{
        
}