from scrapy.spider import BaseSpider

class CnnHomepageSpider(BaseSpider):
    name = 'cnn_homepage'
    allowed_domains = ['www.cnn.com']
    start_urls = ['http://www.cnn.com/',]

    def parse(self, response):
        open('homepage.html', 'wb').write(response.body)

add simple spider that downloads a single page