Running on a Server

So,
I am trying to write a program that runs on my desktop at home and listens to a port. When I send data over the internet to that port on my home computer the program appends it to an html document that I can access by searching my url. The only issue is I am totally confused as to how to run this program so that I can connect and send it information... How do I go about something like this?
I have downloaded tomcat, as I thought perhaps I could make a data entry page hosted on the desktop that sends data to an html generating servlet. Does that make sense? I've not done any web development before, so any help will be appreciated.

u can put that code in jsp page so whenever u send request for that page(jsp) then server will send u the updated web page.

Yeah, JSP makes it easy since you can pass parameters and render html with it. Netbeans makes it easy!

Perfect, I'll use a JSP, thanks for the help!

No problem. I suggest making a simple 'Java Web Application' in netbeans, which will provide you with a sample JSP page and allow you to make class files. If you download the full java version of netbeans, it comes with glassfish server which works pretty well from within netbeans - though for actual deployment, I really like Jetty. Its very lightweight, and rock solid. Good Luck!