What happens in the event that a player gets held up over a try line in rugby? If you could break it down it would be a big help as i have no knowledge of Rugby whatsoever.

5 metre scrum, with the put-in going to the attacking side. IRB Law 22.10.

If the player is held up when trying to plant the ball in the opposition try-line, the ball is deemed 'dead' and therefore results in a 5 metre scrum to the attacking team.

You don't specify Union or League? In Rugby League, when a player is held up, they play-the-ball 10 metres out from where they were held up in goal and the normal tackle count continues.