This page is actually a static web page that "calls up" a dynamic web page from the http server. Below are two HTML Forms that send two parameters to the http server which passes those two parameters to a process (running on the server) that computes the dynamic web page that is returned to this client.
For each http method, GET and POST, look at the URL for the resulting dynamic page.
Be sure to watch the http traffic using some version of "Live HTTP Headers".
You can think of generating dynamic content as needing several steps.
In this example page, first an HTML Form is used by the browser to get parameters from the user. Second, either an http GET or an http POST is used by the browser to send the parameters to the http server. Third, in this example the CGI protocol is used by the http server to start the adder.exe process and send it parameters by using environment variables. Fourth, according to the CGI protocol, the server redirects adder.exe's standard output stream to be the server socket's output stream (so adder.exe's output goes straight back to the clients browser).
Try the Ajax dynamic web page.
Try the web page of various "application servers".
Go back to the static web page.