1- Using the AirVisual app: Open the AirVisual app, click on the middle "+" sign > "Manage my devices & Wi-Fi" > press the small Wi-Fi icon or "Configure Wi-Fi" for a registered device, if available. Follow the instructions.
2- Using the Node/Pro itself: Press the center button for settings menu > 'Network', you should see the available networks. Select the Wi-Fi you want and use the virtual keyboard to enter the Wi-Fi password to join.
Make sure that your Wi-Fi network doesn't require web authentication (this is common in hotels, offices and public Wi-Fi hotspots). Web authentication is not supported by the Node/Pro: http://support.airvisual.com/knowledgebase/articles/953269-connecting-the-node-to-wi-fi-networks-with-web-aut