I think that you need to expand a little on what you are trying to do for a good answer.
I suspect the best bet would be to figure out the correct response string to post to the server directly.
e.g.
http://theserveraddr/responsepage.asp?parameter1=firstparam¶meter2=secondparamer
The above would then be sent as a string to the server concerned on port 80 using the TCP/IP support vi's
This avoids any page reformatting issues if the web pages is changed and does not require you to interact with a 'Window'
The exact response string will of course depend on the server and application.
Note
This is a simple example.