Since this topic has been extensively covered in many recent threads, you might want to do a search of this site in order to see all of the responses. But, if you want a quick and dirty summary, I will give you one: While warming up your engine will not harm the engine, it definitely harms your wallet and the air that we breathe, and is absolutely unnecessary in modern cars with fuel injection.
If temperatures are sub-freezing, you might want to wait for as long as 30 seconds before driving away–slowly. Driving gently for the first few miles actually warms the engine AND THE TRANSMISSION far more quickly and far more effectively than idling does.
The best source of information on this topic is sitting in your glove compartment, so I would suggest that you take out the Owner’s Manual and read up on this topic, as well as others.