How Do I add a screengui(or any decendant) to PlayerGui?

Here's what I have so far:

local player = game.Players.LocalPlayer
local playergui = player:WaitForChild("PlayerGui")





for i, v in pairs(game.Players:GetChildren()) do 
	
	v.PlayerGui.ScreenGui.BillboardGui.Textlabel.Text = "Congrats, it worked"
	
end
	
	
	

as you can see on line 4 im mentioning a screengui and its decendants but they dont really mean anything because they dont exist. But how do I add billboard gui etc to the player gui?