How can I have WiFi on my phone

Connect to Wi-Fi on your iPhone, iPad, or iPod touch - Apple ...Official Apple Support › en-us

Open Settings, tap Wi-Fi, and turn on the switch. Then tap a network to connect to from the list that appears and that you know the password for.

By enabling Wifi option in Settings, and knowing the wifi network SSID & password.

If you mean something different, please specify your needs/problems better.

Thanks and regards

Giulio