If you can't get a member of staff directly on the server, you can always make a report abuse thread in this section:
zarpgaming.com/index.php/forum/report-abuse
Just copy this template and fill out the details, make sure to submit valuable evidence!
[b]Name[/b] - (What is the accused person's name?)
[b]Steam-ID[/b] - (What is the accused person's Steam-ID?)
[b]Evidence of Steam-ID[/b] - (Screenshot or video of the accused players Steam-ID)
[b]Server[/b] - (What server was this on?)
[b]Time and date (CET)[/b] - (When did it happend?)
[b]Other comments[/b] - (Anything else you want to add?)
[b]Reason[/b] - (What rules did the person break?)
[b]Story[/b] - (What happened?)
[b]Proof[/b] - (Any proof (video or screenshot) that clearly shows what happened.)