.NET interface with website

[ThermoSight]

I would like to write a .NET/C++ 'agent' application which will log on to a single, specific website, begin communicating with that website via bidirectional ascii strings, and when the appropriate information appears, email the user.

The problem is that I haven't clue 1, as to how to do this. I think I can do the logging on OK, I'm familiar with connecting to servers et al, but it's the communication that has me stumped.

If my agent application were to execute MSIE, would it be able to access IE's text boxes to 'see' the strings moving back and forth? Could the agent somehow enter strings into the text box and activate the communication as if the 'GO' button had been pushed?

What is the procedure for talking to a website? Is this XML?

Thanks for any help you may be able to provide.

bill