1. Click the Network icon, which looks like   in the task bar at the bottom right. A list will now appear with all the available Wi-Fi networks.
2. Select your Wi-Fi network. 
3. Checkmark the Connect automatically box if you want your tablet or PC to connect automatically to this Wi-Fi network. Click the Connect button.
4. Enter the password of the Wi-Fi network. Click Next.

If these explanations are insufficient, see on microsoft.com how to connect to a Wi-Fi network .