Sheff21, you need to learn first about HTTP. And how data is sent to a web page via GET or POST.

You send a request to a Web page via the GET or POST method, if you have done some basic web programming or written some forms in HTML you would have encountered them, or you could read about them in the page I have linked to HTTP.

Also once you have cleared your HTTP concepts, Here is an example on how to perform POST in Core Java.
Performing a GET is as simple as appending the the URL with a "?" and then appending the data with the format <param1>=<value1>&<param2>=<value2>& ... &<paramN>=<valueN> and invoking it.