import urllib2
import cookielib
import urllib
import requests
import mechanize
from mechanize._opener import urlopen
from mechanize._form import ParseResponse

USERNAME = 'Test'
PASSWORD = 'bla123'
URL      = "http://www.magickartenmarkt.de"

# first approach
request = mechanize.Request(URL)
response = mechanize.urlopen(request)
forms = mechanize.ParseResponse(response, backwards_compat=False)
# I don't want to close?!
#response.close()

# Username and Password are stored in this form
form = forms[1]

form["username"] = USERNAME
form["userPassword"] = PASSWORD

#proof entering data has worked
user = form["username"]  # a string, NOT a Control instance
print user
pw = form["userPassword"]  # a string, NOT a Control instance
print pw
#is this the page where I will redirected after login?
print urlopen(form.click()).read ()

#second approach
cj = cookielib.CookieJar()
opener = urllib2.build_opener(urllib2.HTTPCookieProcessor(cj))
login_data = urllib.urlencode({'username' : USERNAME, 'userPassword': PASSWORD})

#login
response_web = opener.open(URL, login_data)

#did it work? for me not....
resp = opener.open('https://www.magickartenmarkt.de/?mainPage=showWants')
print resp.read()

browser = mechanize.Browser()
browser.open(YOUR URL)
browser.select_form(nr = 0)
browser.form['username'] = USERNAME
browser.form['password'] = PASSWORD
browser.submit()