You have to tell the TV the source of INPUT (which HDMI or source)...
You should have the Roku Home screen on the TV.
Go to Settings/Network/Setup connection choose wireless
back one and /Check Connection
Go to here if you need to; https://community.roku.com/t5/Network-Wireless-Wired-Connections/Network-Troubleshooting-Help/m-p/51...
Everything seems hard the first time. Once you get through it youll be an expert so hang in there.
---A problem clearly stated is a problem half solved---.