If you are going to verify your site on google.
Pick the html googlefile option.
Stick the googlefile.html (or whatever it is called) in your root of the install. If you installed oxwall in a folder within the host stick it there.
eg: oxwall install
www.site.com the file will be
www.site.com/googlefile.html
or
www.site.com/oxwall then stick it in
www.site.com/oxwall/googlefile.com
Once you have the google file uploaded in the root of your site install edit the .htaccess file to allow google to read it.
Enter this line in your .htaccess file in the root of your site install...
RewriteCond %{REQUEST_URI} !/googlefile.html