Hi Jyotsana, you can manually set proxy settings of a browser using Python Selenium Webdriver this way:
from selenium import webdriver
from selenium.webdriver.common.proxy import Proxy, ProxyType
prox = Proxy()
prox.proxy_type = ProxyType.MANUAL
prox.http_proxy = "ip_addr:port"
prox.socks_proxy = "ip_addr:port"
prox.ssl_proxy = "ip_addr:port"
capabilities = webdriver.DesiredCapabilities.CHROME
prox.add_to_capabilities(capabilities)
driver = webdriver.Chrome(desired_capabilities=capabilities)