Help with GUIs inside a normal script?

game.Players.PlayerAdded:connect(function(player)
    while wait() do
        local level = player:WaitForChild("leaderstats"):WaitForChild("Level")      
        local exp = player:FindFirstChild("leaderstats"):FindFirstChild("Exp")
        local extraLevel = level.Value
        local expNeeded = ((extraLevel * 2) - 1) * 300

        if level.Value < maxLevel then
            if exp.Value >= expNeeded then
                player.Cash.Value = player.Cash.Value + 50
                level.Value = level.Value + 1
                exp.Value = exp.Value - expNeeded
                levelupframe:TweenPosition(UDim2.new(0.5, -150, 0.5, -50), "Out", "Quad", 1, false)
                leveluptext.Text =  "You have leveled up to Level: " .. level.Value 
                player.Cash.Value = player.Cash.Value + 50
                levelupframe:TweenPosition(UDim2.new(0, -300, 0.5, -50), "Out", "Quad", 1, false)
            end
        end
    end
end)

I have this that levels the player up when they get enough exp. But the gui that should show up stays in the center of the screen. Please help.