No...as Slayer said, you don't need decoys to hunt turkeys. In fact unless you have been in multiple situations with birds over the years, as in your case, a new turkey hunter, you would probably put yourself at a disadvantage using one.
There is, in my opinion a real knack to successfully using turkey decoys. You have to read the situation you're in and then decide to use one or not. Then the placement is of paramount importance. Put it in the wrong place and you'll either spook and incoming bird or hang him up. Put it in the right place and dead bird.
That's not to say that turkey hunters have not just stuck out a decoy and have one come screaming in....it happens, but not the norm. I rarely use one.....but there are those times when it will make a difference. In fact I just bought a new one, because I liked the looks of it and also where I plan to hunt is on private lands that we have permission. Still, I will use it or not use it depending on the situation. I've enclosed a picture of it. If you're going to get one ...get a good one.
Safety is another issue. People stalk turkey noises and decoys. Be sure if you decide to use one, you do it with safety in mind. Have a clear view of at least 180 degrees plus so you can see anyone coming before they are within range of you, and have your back to a tree wide enough to shield you from incoming shot.