The following bit of code goes in your .htaccess file and forces users to use your sub-domain as opposed to your sub-folder. In example, it forces users to use example.spechal.com and does not allow them to use spechal.com/example

RewriteEngine On
RewriteCond %{HTTP_HOST} ^(www\.)?spechal\.com
RewriteRule (.*) http://example.spechal.com/$1 [L]

Apache, mod_rewrite