Article: If the network does not broadcast its name (SSID), you can add it manually.          If the network is in range and you entered the information correctly, your device will connect immediately. If the network is not in range, your device will connect automatically when it detects the network.

What is a summary?
Press the Home button on your device. Tap the Apps button. Open the Android's Settings. Tap Wi-Fi. Tap the ⋮ button in the upper-right corner. Tap Add Wi-Fi. Type the SSID (network name) of the hidden network. Tap the Security menu. Tap the type of security that the network uses. Type the network's password in the field that appears. Tap Connect.