Two articles introducing IPv6.
http://www.windowsnetworking.com/articles_tutorials/Crash-Course-IPv6-Part1.html
http://www.windowsnetworking.com/articles_tutorials/Crash-Course-IPv6-Part2.html
It introduces the IPv6 address space and how it is represented normally and in HTTP URL.
Then it explains the significance of various bits in an IPv6 address; what is site-prefix, subnet-ID and interface-ID; unicast, multicast, and anycast.