Make sure your Wifi is on & connected. Swipe down in the upper right corner of your iPhone to access control center.
Make sure Wifi is highlighted blue to ensure connection.
Ensure you have the correct password for the Wifi network you are trying to connect to.
Ensure your OS system is up to date.
Still Not Working?
To ensure your device connectivity is not the issue please then restart your device. Restarting your device is done by holding the up volume button and the power button at the same time. Once done you should see an slide to power off option to power down.
No results? You may need to reset your network settings! That can be done by..
Settings>General>Reset>Reset network settings. Your phone would reboot and you would connect to the Wifi by finding it's name & entering the password.