Not getting an IPv6 address?

Hi

comcast6.net says:

Your CMTS is ready for IPv6. Please check this website for modem support. - See more at: http://mydeviceinfo.comcast.net/?s=i&so=1&e=0&d2=0&d3=0&tier=-1&sc=570

My modem is a self-supplied SB6121, which that link says supports IPv6.

What else do I need to do to get IPv6?

Thanks