Text Display Question.

I have a quick and easy question. It's how do I send a message to just one player, the player who triggered an event? Say for example, a unit enters playable map area, I want to send that player and only that player a message saying what that unit can do.

I have a related question, can I send one message to every player except for one, and send a different message to that one player?
For example, I have 6 secret heroes in my map, and when a player activates one through a riddle or what-not I want to send a message to everyone saying, "Someone has activated the Soul Stealer Hero." I then want this message to go to that one player, "Congratulations on solving the Soul Stealers Riddle, you may now type in this code to use the Soul Stealer in any game you play. Remember to keep the code, and the riddle answer to yourself.".

Event-unit enters region
Action: Game-display to (player group((owner of (triggering unit)))) the text: blablaBLA!

or display it to all players