First, you need a Lifeprint printer that supports Wi-Fi capabilities. As of today, only the Lifeprint 3x4.5 printer supports WiFi Connection.
Once you have confirmed you have a 3x4.5 printer, just turn on your printer and connect to it via Bluetooth. Then, make sure that your phone is connected to the WiFi network in your home you wish to use. Currently, only 2.4Ghz connection points are supported. So, if you are connected to a 5GHz connection, please shift your phone WiFi connection to a 2.4Ghz connection point. Once this is done, open up the Lifeprint App and select the "Config" button on the Printer Utility Screen. An alert will pop-up asking for your permission to use your phone WiFi configuration. From there, the printer will then attempt to connect to WiFi. You will see the blue LED light on your printer flash, as it attempts to connect. Once a connection made, the light will turn solid blue, and you should have a drop-down notice indicating that the configuration has been successful. Keep in mind that, while your printer may be connected to WiFi, it will prefer to use the Bluetooth connection while that exists. The WiFi connection will kick in once your Bluetooth is no longer connected or in range.