url setting for directry

I want to make a setting for the url. If a user entered url in address bar like this "folder.mysitedomain.com" then it should be open files from second layer directory named 'folder' of the 'mysitedomain.com'(root directory) at server. A user can also put url just like this "mysitedomain.com/folder" then it also done as above. Url will show as well as user entered. This should be dynamically, for example directories are creating accrording to separate user accounts, so the name of the directory may be anything as dynamically. I think it is for .htaccess files setting. is there ? I have no idea about this that 开发者_如何学编程what i should to do and how to search this in Google and any searching site.

Help should be happily.

I'm not completely sure what you're trying to do but I think you should check out glob

http://php.net/manual/en/function.glob.php

That should get you started anyway.