You need to configure the wan interface with the wan IP provided (forget the wan ip block etc – all you need is IP address, gateway info and subnet mask.
Then configure the ethernet interface with an ip from the address block they gave you; I’d have to check the exact procedure for enabling the communication on the 17xx router, but make sure you don’t forget to bring up both interfaces and you should be golden. I would plug the router into some type of firewall/dhcp device, and assign private ips to the end user machines, nat’d by the firewall. then forwarded to the router.
hope this is somewhat helpful