need help getting error when trying selenium with python

[Ansuman Suryaprakash]

pyhton version 3.5
selenium version 3.0.2
firefox version 50.1.0


pyhton code:

from selenium import webdriver

browser = webdriver.Firefox()
browser.get('http://127.0.0.1:8000')

assert 'Django' in browser.title

Error:

D:\django_learning_TDD>py functional_tests.py
Traceback (most recent call last):
  File "functional_tests.py", line 3, in <module>
    browser = webdriver.Firefox()
  File "C:\Users\Subhasish\AppData\Local\Programs\Python\Python35-32\lib\site-pa
ckages\selenium\webdriver\firefox\webdriver.py", line 140, in __init__
    self.service.start()
  File "C:\Users\Subhasish\AppData\Local\Programs\Python\Python35-32\lib\site-packages\selenium\webdriver\common\service.py", line 102, in start
    raise WebDriverException("Can not connect to the Service %s" % self.path)
selenium.common.exceptions.WebDriverException: Message: Can not connect to the Service geckodriver


Can someonr help me with getting rid of the above error