I have a Vizio, and have it connected to Alexa. Provided your Vizio TV is able to work with Alexa, you have to set it up on the TV, then connect it to your Alexa account. Here are a couple of links I think you will find useful:
https://support.vizio.com/s/article/Alexa-SmartCast-Display?language=en_US
https://www.vizio.com/en/alexa
Please make sure your Vizio is capable of linking with Alexa before proceeding with the steps in the above links.
