Router Configuration for ISP (Optimum Online)

Hi
I have a 800A series router that I wish to configure for my home ISP (Optimum Online). I have not availed for the Optimum Business option, which means I do not have a Static IP for myself. Since the IP allocation is going to be dynamic, how do I set my port (NAT for outside) to receive IPs dynamically. I was told of an option using DHCP-Helper.
So can any one help me set this up…? Pl make necessary assumptions where ever needed.