title: Python Web Crawlers and "getting" html source code
body: <p>So my brother wanted me to write a web crawler in Python (self-taught) and I know C++, Java, and a bit of html.  I'm using version 2.7 and reading the python library, but I have a few problems
  1. <code>httplib.HTTPConnection</code> and <code>request</code> concept to me is new and I don't understand if it downloads an html script like cookie or an instance.  If you do both of those, do you get the source for a website page? And what are some words that I would need to know to modify the page and return the modified page.</p>
  
  <p>Just for background, I need to download a page and replace any img with ones I have</p>
  
  <p>And it would be nice if you guys could tell me your opinion of 2.7 and 3.1</p>