requests_login.py

import requests
from bs4 import BeautifulSoup

headers = {
    'user-agent': 'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.99 Safari/537.36'
}

login_data = {
    'name': '<username>',
    'pass': '<password>',
    'form_id': 'new_login_form',
    'op': 'Login'
}

with requests.Session() as s:
    url = 'https://www.codechef.com/'
    r = s.get(url, headers=headers)
    soup = BeautifulSoup(r.content, 'html5lib')
    login_data['form_build_id'] = soup.find('input', attrs={'name': 'form_build_id'})['value']
    r = s.post(url, data=login_data, headers=headers)
    print(r.content)

@uminostech1089 you need to send the request the same way, the browser sending to the server. Use fidler or any http network debugging tools to read how the website is sending the requests to the server