You need to actually make that code run. Putting code in a class doesn't do anything by itself.
Put this in a weapon:
PHP Code:
//#CLIENTSIDE
function onWeaponFired() {
player.chat = "Whoa, 'tis workin'!";
}
And add that weapon to your player. When you fire the weapon your chat should change.
Now, just replace that line in the middle with your GUI-creating code, and it should create.