How to setup online streaming

Just cut the cable. I now have an Tivo Roamio OTA connected to router by Ethernet. Also run windows 7 on my desktop. Signed up for the 14.99 charge with Tivo. New digital antenna on the roof works great for OTA. What do I need to do to get streaming content from online.
Also I liked the Discovery channels and wonder what the is best way to get them without purchasing individual episodes from the likes like Amazon.

Thanks
John