External texts on press


I downloeded a sample dynamic text tutorial from this site. I wanted to change the script to load text files saved as text.1.txt, text2.txt, text3.txt…etc when you click a button.
I just couldn’t get it work.
Imagine a next/back button in a photo gallery which loads captions if you click on the next button it loads text.1txt, then on the next press it loads text2.txt…and so on. And the back button loads the last, I mean if it text4.txt, on press it loads text3.txt.

I knew this method with the old loadVariablesNum (I used a variable and on press the code added 1 to the current loaded textfile’s number)but it doesn’t work in Falsh 8.
Can someone help me write this code with LoadVars and the explain the know-how?