Loading dynamic text

I’m having some trouble getting this started. What I want to do is:

[LIST]
[]I have a text file full of 1 sentence customer testimonials (which I want to keep adding to)
[
]I want to create a flash file that chooses one randomly, shows it for 20 seconds, chooses another one randomly, shows it for 20 seconds, and so on.
[/LIST]
How should I set about doing this?

Thanks.

Mike