You need to plug the TV into a WiFi access point that has a "client" mode. Configure the access point on a computer then move it to the TV.
My personal experience is that Panasonic's online services are maintained poorly, both in TV firmware and on the server side. Since you already need external hardware to make the TV work, I recommend a Roku, Apple TV, mini desktop, laptop, etc. connected via HDMI. Borrow a long Ethernet cable to try out the TV's native services to see what you think of it before spending money on a solution.