To answer your specific question, you need to escape the quotes, or use a different type of quote on the string itself:
addressStart = page.find("<div id=\"address\">")
# or
addressStart = page.find('<div id="address">')
But don't do that. If you are trying to "parse" HTML, let a third-party library do that. Try Beautiful Soup. You get a nice object back which you can use to traverse or search. You can grab attributes, values, etc... without having to worry about the complexities of parsing HTML or XML:
from bs4 import BeautifulSoup
soup = BeautifulSoup(page)
for address in soup.find_all('div',id='address'): # returns a list, use find if you just want the first
for info in address.find_all('div',class_='info'): # for attribute class, use class_ instead since class is a reserved word
print info.string