You can report users in-game and the forums in this section here:
zarpgaming.com/index.php/forum/report-abuse
All the information you will need on reporting a player/staff member is found as a pinned topic within that section at the top of the page.
May I also remind you too that you shouldn't be breaking rules as well, two wrongs do not make a right so the best you can do is to just report them instead of breaking rules yourself. I understand you were trying to help but it might just encourage the behaviour as well.