I bought this laptop and it has wifi built in so of course I have to get wifi so I can try it right

Right now I have a regular wired linksys router. Does anyone know is there a device that would connect to a ethernet jack on the router and let me access it using wifi or do I have to just get a new router with it built in.

I have found external devices like this that connect to the ethernet on a pc to connect it to a wireless network but I don't know if that would work if connected to the router.