It is not recommended to use XAMPP as a live production server as outlined in the \xampp\readme_en.txt file.
A forum search for some of the keywords in your first post or even Joomla may have an up to date tutorial on how to do what you want.
Sorry, this forum does not usually help out directly those wanting to use XAMPP for anything but it's intended purpose - XAMPP has security settings for developing at localhost level not for an open server to the Internet.
There are alternative production servers that you could use, see Alteas signature here for a free alternative production server to XAMPP:memberlist.php?mode=viewprofile&u=41947
Good luck with your forum search as I am sure you will find the answer, also Google will have the answer in the form of a tutorial for sure.