How do I set up my old Sega Genesis 3 with a modern tv?

I have an Advent tv and an RF adaptor, but I don't know what to connect. I tried connecting a few different things and switching through component 1 + 2, video 1, 2, and 3, and I tried both channels 3 and 4 without any results. Am I not setting it up right, or am I missing an adaptor or what?