!!Making a cgi script that updates CJB.net website address!!

[123456programmer]

Hey.
I have my own computer running as a server. But since i don't have much money i can't get a static IP neither a .com domain name. so i m actually using no-ip.com.

Let's say my IP is 192.168.xxx.xxx
and let s say there are three different websites on my server. i have one folder for each website.
i have one site that is about music, which is located in the folder named "mp3" on my computer, one site about sports which is in a folder named "sport" and one site that is about the internet which is in a folder named "internet".
i want three different redirection like this:

http://192.168.xxx.xxx/mp3

->

http://mp3.cjb.net

http://192.168.xxx.xxx/sport

->

http://sports.cjb.net

http://192.168.xxx.xxx/internet

->

http://internet.cjb.net

I have to disconnect few times a day the ROUTER from the internet, and each time im disconnected from my ISP the "xxx.xxx" part of the IP changes.
And because i have got many sites i can t keep on refreshing the ip each time i m disconnecter.

So what i want, but i can t do on my own, is to make a cgi script that i can run from my computer, that checks my ROUTER'S IP, that signs in my cjb.net account(everytime i run my cgi script) and that updates only the IP address.
Thanx for your attention.