I would like to show how I would do to pass an input to the HTML. I usually use python to send request to the page where I need to input the data. Before doing that you need to know if you need to supply web-cookies or not, if yes, copy the cookie, if you need to be logged in otherwise not, just check that. Once that is done, you need to know the field names for the input area as you will be using them to POST or GET data using your script. Here is sample usage.
import urllib
import urllib2
import string
headers = {'Cookie': 'You cookies if you need'}
values = {'form_name':'sample text', 'submit':''}
data = urllib.urlencode(values)
req = urllib2.Request('website where you making request to',data,headers)
opener1 = urllib2.build_opener()
page1=opener1.open(req)
#OPTIONAL
htmlfile=page1.read()
fout = open('MYHTMLFILE.html', "wb")
fout.write(htmlfile)
fout.close()