Just opening a file doesn't make output go there, you need to write to it:
fout = open('Users.txt', 'w')
fout.write(ent.get())
...
Or better, use a context manager
with open('Users.txt', 'w') as fout:
fout.write(ent.get())
As far as suggestions to clean things up, I would use loops to create the widgets and lists to store them.