@Callum Telf First of all you need to set a key to push-to-talk in the multiplayer section in the control options of arma. I will include a short video on how to get there ;)
Oh yeah, you want to use "direct communication" when you are standing in front of someone or in general when you are on foot. If you are in a vehicle (car/truck/heli) you need to use the vehicle channel. Be careful the vehicle channel is a bit louder so don´t try to scream in it ;)
Make sure you have the correct channel enabled and your push-to-talk button is correctly mapped. Otherwise check your mic in windows and if people can hear you on teamspeak.
Your In-game name
SGT Jedd Lii
Name of the player(s) you are reporting
Strix
Date of the incident
01/25/2016
Time of the incident (GMT)
22
What best describes this incident ?
Other
Which server did the incident take place on
Server 2
Please (in detail) describe the incident
I was in...