You're trying to access "from another house" ?
So you need some way to tell the world that there is a machine on the Internet (on your local network) that will answer that request, and you've started with forwarding the port - good job. Most people forget that.
The DNS needs to be updated with a hostname that resolves to the IP address of the machine where you've installed XAMPP. A free option is to create an account with Dyndns.com, and choose a domain name of your liking. Then download, install and configure their dynamic update client - this will update DNS whenever the IP address of your "server" changes.
If you want to access your site from within your own network, its easier to add entries to your hosts file (
%SystemRoot%\System32\drivers\etc\hosts) on Windows, or /etc/hosts on *nix, because you may want to get into virtual hosts later on. :)
Add a line:
A.B.C.D is the IP of the machine where XAMPP is installed (eg.
192.168.1.2) and save it.
Then, you can access your website with:
If you do decide on a dynamic domain, you can use the same domain name in your hosts file also - like
Reference: Do It Yourself Web Server / Hosting - Lessons