What do you mean 'each message has its own effect'?
Edit. Which don't you know? Just to narrow it down..
How to do something at certain time intervals
How to choose something randomly
How to display something in a 'textbox'
How to store and retrieve a large number of text values
How to display an effect on a text object
All of the above
How to put it all together
Also, how does the topic title refer to your question? Edit: oh ok, the every x seconds thing..(?)