A popular teacher at a Brooklyn parochial school is in hot water after a sixth-grader stumbled onto his gay personal home page - then got punished in front of classmates. Denton Black was pulled out of his classroom at the St. Mark's Day School in Crown Heights last week after 11-year-old David Brown E-mailed the teacher about a homework assignment and was exposed to the racy Web page. ...The day after David's mother complained to school administrators last week, the boy was forced to stand in front of his class for more than an hour, Greenwood said.