Probably dumb ? But I'm new to this!

[BrittM87]

Okay, this maybe a dumb question but I have never had chickens before! So I'm trying to figure out who in my flock is a rooster and who is not!!! I got Orpingtons back in April and som are larger than others, some combs are brighter and bigger and I just don't have a clue!! Here are some picks... I have 1 black orpington that I'm pretty sure is a rooster but I want some others to tell me! Then I have buffs that I'm not sure of!

 

[BrittM87]

This is all I have. They don't like to Stay too still for me!