I want to stream netflix to my tv...do I need a router..?

-If I bought a roku stream device and connect it to dsl internet connection(ethernet) would it work...cuz on the site it says something about a router. i also get wireless internet cuz were connection local network.so my question is do I need router or can I hook the ethernet cable straight to roku and the wall....I dont think I have a modem or router...somebody please help me!!!