How do I connect my Apple TV book to WiFi

Welcome to the Apple community.

Try this:

https://support.apple.com/en-us/HT204400

What is your model Apple TV? Identify your Apple TV model - Apple Support

How do I connect my Apple TV box to WiFi

The same as any other connected device. Go to network settings, select the Wi-Fi network, enter the password, and you’re connected. Get help with Wi-Fi networks on your Apple TV - Apple Support