FORM filling using JAVA

here's the task:

i got a program and a word file.
the program has some input fields and the word file contains the corresponding words to be put in input fields.
so, i want to write a java program that will open that program and fill the input fields copying from the word file.
the program is basically a form.

thanks in advance.

i know how to open a program through a java program(using Process proc = Runtime.getRuntime().exec(); )
but i don't know how copy a word from a file and paste it into another