Using FindFirstChild to make a gui appear?

Hi, I'm BlackOrange and I will be helping you out.

#Problem:#

1. You did not specify what type of script this is
2. You're looking in the wrong place.
3. You need RemoteEvents

#Solution:#

A simple solution is to restart. First add a RemoteEvent to ReplicatedStorage. You can name it anything you want but I'm going to leave it as RemoteEvent. Next, go to your part and insert a Script. Inside the script you wanna start by a Touched event:

script.Parent.Touched:Connect(function(Hit) -- Assuming script.Parent is a part

end)

Now what you wanna do is add a LocalScript into the frame you want to appear. After that go to the LocalScript and type:

game.ReplicatedStorage.RemoteEvent.OnClientEvent:Connect(function() -- When the client receives a FireClient from the server the code will run
	script.Parent.Visible = true -- Make the frame visible
end)

Now head back to the script and what you wanna do is get the player. The method we are going to use is :GetPlayerFromCharacter(). First we want to check if a player touched the part though.

script.Parent.Touched:Connect(function(Hit)
	if Hit:IsA('BasePart') and Hit.Parent:IsA('Model') and Hit.Parent:FindFirstChild('Humanoid') and game.Players:FindFirstChild(Hit.Parent.Name) then -- This is a fairly long line but this checks if this there is a humanoid and if it's a player.
		local Player = game.Players:GetPlayerFromCharacter(Hit.Parent)-- get's the player
		game.ReplicatedStorage.RemoteEvent:FireClient(Player) -- sends a signal to the player
	end
end)

And you're done! Hope you learned something.

Best of luck developer!

EDIT: This was written from scratch, if an issue occurs please comment.