How to rank players in game?

Hello

I want to make it able to rank players in game like with :rank player soldier the player gets automatic ranked to soldier in the group. Also I want that only me and some other people can do that. I know that this must be possibole cause I saw this at roblox dino daycare If you know please tell me! Sorry that i don't have codes orso I'm new to scripting

Thanks

Kees