windows'chromedriver' executable needs to be in PATH. Please see https://sites.google.com/a/chromium.org/chromedriver/home code example

Example: Message: 'chromedriver' executable needs to be in PATH. Please see https://sites.google.com/a/chromium.org/chromedriver/home

You can download ChromeDriver here: https://sites.google.com/a/chromium.org/chromedriver/downloads

Then you have multiple options:

add it to your system path
put it in the same directory as your python script
specify the location directly via executable_path

driver = webdriver.Chrome(executable_path='C:/path/to/chromedriver.exe')