When you first open up CCC, do you have it set for Advanced View? There's a "Preferences" button on the top right of the window.
On the left side, the 7th button down is "My Digital Flat-Panels". Select one of the HDTV resolutions that most closely matches your TV's capability and add it. Once you've applied that resolution, you will be asked to drag the borders of the box to adjust the overscan. It's just that simple.
i7-6700K, NT06-Pro, GA-Z170N-Gaming5, 32 GiB, RX Vega56, SM951, 5TB HDD, Blu-ray, FTZ01, SX800-LTi, C32HG70, RK-9000BR, MX518