Delayed message in chat

[Nodos7]

Hello, world!
I have this simple code:

function ButtonHelp_OnClick()
	if UnitIsPlayer("target") or UnitName("target") == nil then
    SendChatMessage("I need help!");
    SendChatMessage("Somebody, help!");
    else
	SendChatMessage("Help me, target!");
        SendChatMessage("Target, please!");
    end
end

How can I send a second message after first message in 3 seconds? Is there any timer for this in vanilla wow?