Follow the below steps:
1. Tap on Settings from the home screen > Wi-Fi, and make sure Wi-Fi is turned on. Then tap Other
2.Enter the exact name of the network, then tap Security.
3.Choose the security type. Not all hidden networks are secure. If you're not sure, check with your network administrator.
4.Tap other network to return to the previous screen
5.Enter the network password in the Password field, then tap Join.
After you join the network, you'll see a blue tick next to the network and the wifi icon in the upper-left side of your display.
You will now be connected to the hidden Wi-Fi Network and no further steps is needed.