I've installed two plug-ins that give me an instruction like this:
using FTP or your server admin panel, change the permission of the CSS theme files to 666
Use your favorite FTP program to create two files in your WordPress directory (that's where the wp-config.php is) named sitemap.xml and sitemap.xml.gz and make them writable via CHMOD 666.
in both cases the instructions, to me, are very vague. In what file do I change these permissions? There are lots of instructions about how to change, but I'm not sure where to make these changes. No files that match those indicated exist.
Any ideas? Thanks.