Onclicked? script? help? needed

I need help on my new script. The help i need is that i want it so that the person presses a button using gui's and then the shirt and pants appear on the human.

--Made by codboy22


local shirtTemplate = "http://www.roblox.com/asset/?id=59323775" 

local pantsTemplate = "http://www.roblox.com/asset/?id=59404936" 

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local faceID = "" 



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local delete_Tshirts = true 	

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-- Main coding:

function changeClothing(p)
	 
	if (p.Character) then 
		local shirt = true 
		local pants = true 
		local face = true 
		if (shirtTemplate == "") then shirt = false end 
		if (pantsTemplate == "") then pants = false end 
		if (faceID == "") then face = false end 
		local S = Instance.new("Shirt") 
		S.Name = "Shirt" 
		S.ShirtTemplate = shirtTemplate 
		local P = Instance.new("Pants") 
		P.Name = "Pants" 
		P.PantsTemplate = pantsTemplate 
		for _,v in pairs(p.Character:GetChildren()) do 
			if (v.className == "Shirt") then 
				if (shirt) then 
					v:remove() 
				end 
			elseif (v.className == "Pants") then 
				if (pants) then 
					v:remove() 
				end 
			elseif ((v.className == "Part") and (v.Name == "Torso")) then 
				if ((delete_Tshirts) and (v:findFirstChild("roblox"))) then 
					v.roblox:remove() 
				end 
			elseif ((v.className == "Part") and (v.Name == "Head")) then 
				if ((face) and (v:findFirstChild("face"))) then 
					v.face.Texture = faceID 
				end 
			end 
			if (shirt) then 
				S.Parent = p.Character 
			end 
			if (pants) then 
				P.Parent = p.Character 
			end 
		end 
		print("Changed " .. p.Name .. "'s clothing") 
	else 
		print(p.Name .. "'s character was not found; function returned") 
		return 
	end 
end 

game.Players.PlayerAdded:connect(function(p) 
	repeat wait() until p.Character		-- Wait for the new player to spawn 
	changeClothing(p) 
	p.Changed:connect(function(x) 
		if (x == "Character") then 
			game:service("RunService").Stepped:wait() 
			if not (p.Character) then return end 
			changeClothing(p) 
		end 
	end) 
end) 
script.Parent.MouseButton1Down:connect(onClicked)