The webpages on an online server reside in a location which looks somewhat like this: http://www.somerandomsite.com/index.php
Since xampp is Offline, it sets up a local server whose address is like this
http://localhost/
Basically, xampp sets up a server (apache and others) in your system. And all the files such as index.php, somethingelse.php, etc., reside in the xampp\htdocs\ folder.
The browser locates the server in localhost and will search through the above folder for any resources available in there.
So create any number of folders inside the “xampp\htdocs\” each folder thus forming a website (as you build it).
Sometimes apache won’t even start. This is due to the clashing of ports with some applications. Some of them I commonly encounter is Skype. See to that it is killed completely and restart apache