Help with progessing button

Hello, I have a dynamic text field that displays text from an external file. The text file has lists of text such as

a1=(text here)&w1=(text here)& etc

I want to be able to make a button so that will add one to the word count, such as, a button that says “Next” and when i do that, it loads the text string A2, when i click it again, it loads A3. Hopefully someone can understand this to help me out. Please reply or send me a personal message.