Hello World;

I have been trying to make an animation for my research. I have a bunch of prototype output files so called
output1.txt        
output2.txt
output3.txt
output4.txt
...etc

When I feed those files one at a time, I get stay images. What I would like to do is feed all the files
in order in every 0.5 seconds, so I will have 2 frames per second but I cannot figure out how to
update the file sequences in mathematica.This is what I have so far and I am looking for the coding
to update the files automatically.
If you have any ideas, please let me know. Thank You.

-P. Aung