To do this best practice would be to use the official Nintendo Switch dock or wires. You can use the third party but there's obviously a risk that this may damage your system.
The Nintendo Switch Dock includes a port at the trunk under the main flap for an HDMI and electricity cable. Cables for the two these ports should have also been included in the Switch packaging and you'll want to have both plugged in.
HDMI is the current standard video cable, therefore, most somewhat modern TVs have one.
Make note of which interface it's, and then navigate to that section using the source on your tv remote. Take your Shift console sitting in the dock and turn your turn on using the power button along with a controller. This should lead to the image on the Switch appearing on the TV.
If you do not have an HDMI port on your TV you may need to look into buying an adapter or even a new television.