I have to set my apache atmosphere to 'foobar' I understand I have to occur during my vhost, but what must i type there and where?

[cde] sets a specific variable with a value, which means you need something similar to

SetEnv

If this sounds like for any specific virtual host, and you can get the Apache configuration files, this could walk inside the SetEnv varname varvalue directive for your virtual host.

Without having charge of the config files, you will need to place it inside a <VirtualHost> file. However for this to operate, .htaccess should be permitted in SetEnv files, that is specified while using [cde] directive.