Looking for Ranked 3's/5's

Hello all, I'm sort of new to ranked. I got placed in silver 2 yolo-que.

And it has two other options, ranked 5's which I obviously know what that is. But also lists "3vs3's" How would you go about doing ranked 3vs3's?

Also, Im a good top/mid laner and support. I'm not quite used to the adc environment in ranked.