I want login page using 3 tier architecure

string sqlstr = "select * from dbo.Login where username= ' " + Email + " ' and password= ' " + Password + " ' ";
               //adapter logic
               SqlDataAdapter adp = new SqlDataAdapter(sqlstr, con);
               DataSet ds = new DataSet();
               adp.Fill(ds);
               //datatable logic
               DataTable dt;
               dt = ds.Tables[0];
               return (dt);