Cisco 851

I just subscribed to cable for static IP. they just installed in but I’m running into an issue implementing it into my network. I’m told that I don’t have access to the cisco 851 router they’ve provided. I can only get out to the internet if I configure a PC using the static IP address I was provided. My question is how do I implement this into my environment, i’ve tried a few things but it’s not working. I have a watchguard firewall, a linksys router, a switch….optonline provided me with a modem and a cisco 851 router.