Generally the LAN setup is pretty simple; SLAAC (Stateless Address Auto-configuration) and RADVD (Router Advertisements). Personally I wouldn't worry about DHCPv6, especially until things are working, and maybe not even then.
The trickier bit is the WAN setup as this is where the router requests and gets delegated an IPv6 prefix that it can then use on its LAN. Is there another page showing the WAN setup?
EDIT:
It may be different for you, but on my ZyXel 8924 the WAN settings are under the 'Broadband' configuration. Under the IPv6 Address section, select the IPv6 Address 'Automatic' radio button and check the 'Prefix Delegation (IA_PD)' tick box.