How can I make a function that a label appears above a players head if they're in a group?

I need to make a script so that, when a player joins, if they're in a certain group and rank, a name tag appears above their head. The label will say which group they're in and the rank that they're in. How can I do this?

Well to make a function like that, we first need the player.

game.Players.PlayerAdded:Connect(someFunction)

Placing this in ServerScriptService, whenever a player joins, the function "someFunction" will be fired and the player instance will be given to it.

Next we need the group ID.

local groupId = 000 -- Enter group ID here.

Now, inside our function we need to check their role in the group. We can do this as so:

local function someFunction(plr)
	local role = plr:GetRoleInGroup(groupId) -- Will be guest if they are not in the group.
end

Then, we need to create a billboard GUI for the GUI above the players head, and the textlabel displaying the info.

repeat
	wait()
until plr.Character
local gui = Instance.new("BillboardGui", plr.Character:WaitForChild("Head"))
local label = Instance.new("TextLabel", gui)
label.Text = plr.Name .. role

All done! Well, almost. There are a few problems with the code but I will leave that up to you. I have given you the bulk of what you need to know!

Apologies for any grammatical errors.