hi
I have just started playing CSS
and having bad problems
when i play i teamkill because i dont know whos who lol

and how can i chat? because i seen others chatting at the bottom and talking through speakers

how can i do it?

press the y button once to enter chat mode

Default settings for text chat are "y" to send messages to everyone (if you're dead the message will only be sent to dead people), and "u" to send just to your team (again if you're dead then only your dead teamates will see what you are typing).

For voice chatting then you'll have to look through your keyboard settings as I forget what the default is. Just like with text typing if you're dead then only dead people on your same team will hear you unless the server as all_talk enabled then everyone will hear you, whether they are alive or dead. Voice chat is be server default limited to sending messages to your team.

I believe default is "k" for voice chat.