Regardless ot the fact that resetting the password for so many users at once is a really bad idea and setting it to the same one for all of them even with one you have in clear text in a script file is even worse you need to read the TXT file with
or the CSV file with
and you can iterate over the resulting array elements with either
or
Regardless of that … most of the time you’re not the first one with a given task. I’d recommend to use your favorite internet search eingine to search for examples of code you can adapt to your needs. Try to learn from others code - you don’t need to re-invent the wheel again and again.