Sending offers with items

var offer = manager.createOffer(tradeurl); //1. So this is the trade URL of the person I'm sending the trade to right?
			offer.addMyItem(myitem); //2. How do I define myitem? What is the notation / how can I make it take a certain item?
			offer.send(function(err, status) {
				if (err) {
					console.log(err);
					return;
				}