help say

say <what>
say who> <what>
say @who <what>

Says <what> to everyone in the room and those in linked rooms.

If you want to specify a particular person, you can.
For example:
>say orange> Hi.
You say to Orange ‘Hi.’

You can also use this:
>say orange: Hi.
or even this:
>say @orange Hi.

Try putting smilies at the end, e.g. 'say I'm a alien :D'
also try :) ;) :( :'( :x :P :-: (6) :s 8) :O

see also:
tell, yell