How to recieve all my digital cable channels

Hello,

I'm a Comcast subscriber and receive over 150 channels on my 3 different sets with their converter box(s).

I've recently run cable to my basement and can get 2-29 on my set, but nothing after that. I don't have a box hooked up to that set, just running the cable directly into the back of the set. What do I need, outside of renting another box from Comcast, in order to get all the other channels I'm paying for?