I'd suggest to start here:
5. Data Structures — Python 3.9.5 documentation[
^].
Take a look at this small piece of code:
>>> tel = {'jack': 4098, 'sape': 4139}
>>> tel['guido'] = 4127
>>> tel
{'jack': 4098, 'sape': 4139, 'guido': 4127}
>>> tel['jack']
4098
>>> del tel['sape']
>>> tel['irv'] = 4127
So, to add key-value-pair to your dictionaty, you should use:
word_dictionary['your_word_here'] = count_of_word