--just a testing table you can remove this and add the one you have in skin shop script.
local skinSelectionTable = {
	["cj"] = 0,
	["truth"] = 1,
	["maccer"] = 2,
	["andre"] = 3,
	["Barry"] = 4,
	["Barry Big"] = 5,
	["emmet"] = 6,
	["Taxi Driver"] = 7,
	["janitor"] = 8,
	["Normal Ped"] = 9
}

--creating the GUI
function runGUI()
        guiMainWindow = guiCreateWindow(725, 275, 336, 478, "Guard", false)
        guiWindowSetSizable(guiMainWindow, false)
        guiGridList = guiCreateGridList(10, 25, 316, 379, false, guiMainWindow)
        guiGridListAddColumn(guiGridList, "Skin name", 0.5)
        guiGridListAddColumn(guiGridList, "Skin id", 0.5)
        guiCloseButton = guiCreateButton(16, 412, 127, 49, "Close", false, guiMainWindow)
        guiCreateButton = guiCreateButton(189, 412, 127, 49, "Choose Guard", false, guiMainWindow)
        guiSetVisible(guiMainWindow, false)
        -- to hide the GUI after they click "Close" button
        addEventHandler("onClientGUIClick", guiCloseButton, function()
        	guiSetVisible(guiMainWindow, false)
        	showCursor(false, true)
        end)

        addEventHandler("onClientGUIClick", guiCreateButton, createGuardHandler)
        populateGridlist()
end
--opening the GUI with the commandHandler.
function openGUI()
	if not (guiGetVisible(guiMainWindow)) then
		guiSetVisible(guiMainWindow, true)
		showCursor(true, true)
	end
end
-- to add the table to the gridList
function populateGridlist()
	for name, skin in pairs(skinSelectionTable) do
		local row = guiGridListAddRow(guiGridList)

		guiGridListSetItemText(guiGridList, row, 1, name, false, false)
		guiGridListSetItemText(guiGridList, row, 2, skin, false, false)
		guiGridListSetItemData(guiGridList, row, 1, tostring(skin))
	end
end
--creating event to trigger in server-sided in order to create the ped.
function createGuardHandler(button, state)
	if (button == "left" and state == "up") then
		local row, col = guiGridListGetSelectedItem(guiGridList)

		if (row and col and row ~= -1 and col ~= -1) then
			selected = guiGridListGetItemData(guiGridList,row,col)
			selected = tonumber(selected)

			if (selected) then
				--you probably need to change this, couldnt find the CIT message export.
				outputChatBox("Guard has been chosen")
				guiSetVisible(guiMainWindow, false)
				showCursor(false, false)
			else
				--you probably need to change this, couldnt find the CIT error message export.
				outputChatBox("Error")
			end
		end
	end
end
--triggering the event here with a different commandHandler.
function createGuard()
	if (selected) then
		local player = getLocalPlayer()
		triggerServerEvent("createGuardFromGUI", getRootElement(), selected, player)
	end
end

addCommandHandler("guard", createGuard)
addCommandHandler("chooseguard", function()
	if not(guiMainWindow) then
		runGUI()
	end
	openGUI()
end)