Step 1: Place a dog bed or rug on the floor for your designated "Place"
Step 2: Lure the dog to the "place" with a treat, as soon as his feet are on the designated place. mark with a yes, and a treat. Practice this several times until your dog knows to go to the marker to get his treat.
Step 3: Call the place by its name "place" and motion with your hand to the place location , just as he steps into it. YES and treat. Repeat until you can say "place" and he'll go right to it! Now, you can place the bed/rug anywhere in the room where you want your dog to sit or lay down.
Teaching your dog a down command can make this trick helpful to settle in and stay.
If you are looking for a more stable place location, I suggest KLIMBS