Wi-Fi signal originates from your wireless router, it broadcasts a network name that you can recognize called an SSID. When you are on a Wi-Fi enabled device your antenna scans the area for WiFi networks. You then see your Wi-Fi's SSID or name. When you connect to your Wi-Fi it asks for a password, a PSK (pre-shared key), or a network security key, if you have security on. Your device uses that password to authenticate to the wireless router. Then you are connected!
Wifi uses radio waves on the 2.4 Ghz spectrum and the 5Ghz spectrum to communicate with your wireless devices. The wireless router then converts those radio waves over to the ethernet cable which connects to the CTC fiber network.