click on chat to host. If you are lucky a chat box will appear and if you can type a message without getting a host unavailable message you are very lucky. Also the other host must be at their computer... and often they are not.
The feature is very unreliable, and depends on firewalls being correctly configured and upload and download slots being available, among other factors, one of which is luck.
So .. in short .. If you get a chat going... well done ... but dont expect it to happen too often
