you can Scan available Wi-Fi networks after turning on Wi-Fi on HTC One. See wireless networks on HTC One or add network manually by doing as follows:
1. Open "Settings" app
2. Make sure "Wi-Fi" is enabled and tap it
3. Hit the three dot button on the top right, and tap "Scan"
4. The phone scans networks and show you available wireless networks
5. Tap your wireless network, enter password if needed, and Now you are connected.