How report a player?

Yo, i just started bg, i know there is tags like [party] [guild] [battleground] before nickname, and then message, so when i saw message
[battleground] Aemon: Rush left
Aerospark has reported you for being afk, u have 15 seconds to type "/afk" or u will be kicked out of battleground
[battleground] Meme: go lm

So i did /afk, and it kicked me and i have deserter, im kinda confused what happend, how there was message without tag, or its addon or cheat?
Also i was looking for place on forum to report this player but... didnt found it

https://iv.pl/images/6f2f043553466ba...de582ce2c7.png

that is a /emote.

He was trolling (everyone saw that message, not just you)

Typing /afk will kick you from BG.
So, no one has reported you. You have kicked yourself

The real "report afk" mechanism is different.