Can't access the web-site in my home folder from the internet. Need help.

Question

I am trying to publish a website from the Sites folder in my home directory. The website is made and I can access it from from every computer within my ethernet. But despite a couple attempts I made I can not get the website published on the internet.
I have an Airport Express station. Two Macs and one PC are using the ethernet. As far as I can tell the Airport Express station is directly connected to the internet. I live in a brand new apartment which has Lan outlets in every room next to the electricity outlets. I have a single designated internet IP address.
To open my computer to the internet I set the "Default Host Option" in the Airport Administrator Utility and selected the default three digits for the "Default Host option" IP address. Then I updated the Airport Express station, manually set the IP address in the Network preferences on my Mac to the "Default Host option" IP address and activated Personal Web Sharing in the Sharing preferences. By doing so I lost my internet connection. It turned out I still had the same IP address that I had before I selected Default Host Option.
As I understand with the Default Host Option I designate one IP address within the ethernet to receive all traffic from outside. But how do you now tell the Airport Express station which computer on the ethernet will be the host for the incoming traffic carrying the Default Host Option IP address? Apparently just setting the IP address manually in the clients computer Network preferences to the "Default Host Option" IP address doesn't tell the Airport Express station to change the IP address it has assigned to this client to the Default Host Option IP address.
In another attempt to make my website accessible on the internet I removed the Default Host Option and instead opened Public Port 80 and Private Port 80 for the IP address of the client computer in the Port Mapping tap of the Airport Administrator Utility. But again, no access to my website from the internet.
To access the website from within the ethernet I use the following web-link, which works fine:
http://192.xxx.x.x/~user/index.html
The internet of course doesn't see the 193 IP address. It only sees the Public IP address. Therefore I used the Public address instead of the Private IP address to connect to my website from the internet:
http://222.xxx.xxx.xxx/~user/index.html
But as I said, I still can't access the website from the internet.
I have the feeling that I conceptually don't understand something correctly. I would appreciate if somebody could help me with this problem.

Answer 1

See this article:
http://support.apple.com/kb/HT1866
Sometimes My Music does not show up in special folders in TweakUI.
If so, see this post:
http://discussions.apple.com/thread.jspa?messageID=1731188&#1731188##
If you would rather not mess with the registry you can often work round with a shift key start.
Hold down the shift key and start iTunes, keep holding down the shift key until you are asked to choose or create a library. If you already have one, navigate to your iTunes folder and choose iTunes Library.itl. Otherwise create a new library in My music.