What do you want to "cast" - the whole screen, or a video you're playing?
For whole screen casting, both devices must support common casting protocol (usually, Miracast), and I doubt your TV does it. Some phones support MHL (basically, a connector you plug into the phone, with HDMI on the other end).
But I think that the easiest and cheapest would be to get a Chromecast stick for your TV, and use it from your phone.