It's unclear what you want to do. A batch file could prompt for a username and password and if correct launch the website. Batch code cannot pass the username and password to fill in fields on the web page much less click a button.
You would need a scripting language that can create an instance of the browser, navigate to the web page, fill in the name and password fields and click on the sign in button. This is not particularly hard to do, but you would need the source listing of the page to get the names of the userid and password fields and the name of the sign in button.
I would suggest VBScript because it's already installed on your machine, but any Windows scripting language should be able to do this.
