permalinks

I’m going through the documentation at:

http://codex.wordpress.org/Using_Permalinks

to find out why the car-demons plugin:

https://wordpress.org/plugins/car-demon/

inventory listing, http://foo.com/cars-for-sale wouldn’t be working. What other documentation can I reference to understand this problem?

Any pointers for this specific problem? I’m getting an error of:

The requested document was not found on this server.