Mac - how do I read the messages sent to me when Messenger was not running?

Question

Yeah, how'd you guess--I'm new at this.
I use a Mac (OS 10.4) and I glean from the number in the little square on the Messenger icon (when it's running) that I've got messages to read.
Great. How?
Thanks.

Edgar F was good enough to respond to me within 2 minutes or so, "click the square," says he, "It opens Messenger so you can read the messages. Generally."
So now I've got more questions....
When Messenger isn't open, there's no square. When it is open, there used to be the square, but no clear way to get the messages. I'd signed off before getting this response--signed on again, and now the square is gone.
Where'd my messages go, and _now_ how do I get to them?
Thanks.

Answer 1

Which messenger? Yahoo or what?

If it's Yahoo Messenger, your offline messages appear in IM windows when you open the app.

If its Microsoft (MSN) Messenger, I have no clue because I don't use that.

Answer 2

Click the square. It opens Messenger so you can read the messages.
Generally.