Execution Order In Multiple Forms?

am planning to write a simple program which reads two binary files and apply a simple math function ((file1-file2)/(file1+file2)) then outputs the file (file3). Then the user selects the file (file3) outputted as an input and the program again reads the file and apply another math function ((file3 - 0.2) / (0.5 - 0.2)) to it then output the final file (file4).I would like to eliminate the user input or at least minimize the user input. In other words, the user should execute the program once at the beginning and the program should do the rest. Basically there will be 2 form applications in my program. I want to make it automatic in a way that the program will select two files itself (the user should not select) then output the result and then takes that as an input and applies math function etc.My problem is that I do not know how to start the second form application after the first program ends because the second form application inputs the file which was outputted by the first form application.