getting objects to communicate

i'm a beginner scripter and i'm working on some avatar attachments.
and, of course, i would like to create a HUD.
unfortunately, i can't figure out how to make a script in one object talk to a script in another object.
i would look in the lsl wiki, but it's not that easy to read if you're a beginner and don't even know what you're looking for.
what i want to know is what commands should i look up to make a script in a HUD talk to another script?
i don't want someone else to write a script for me as i do want to learn, but i don't even know what commands to look up in the wiki or the forums.
any help would be appreciated.
thanks.

If you're trying to talk to another prim or script in the current linkset, then you may want to check out link messages. (http://wiki.secondlife.com/wiki/Category:LSL_Link_Message) If you're trying to talk to some other kind of object, such as one which is rezzed inworld, then check out http://wiki.secondlife.com/wiki/Category:LSL_Chat.

thanks for pointing me in the right direction, and pointing out that the answer was right in front of me all the time within the linden's default "hello avatar" script.
it worked, and now to dig up the last couple of commands i need, and i'll have everything i need to make a useful HUD.

p.s.
/me jumps up in joy and shouts to the digital sky "IT WORKS!"