Create a new scene and reset it. We are going to model the walls of the room in 3D Studio MAX ( 3ds max ). The walls, floor, roof etc of a room can easily be modelled using boxes. From the Create panel, within standard primitives choose Box and in the top viewport, draw a box. In the modify panel change its length to 500, width to 600 and height to 10. This box, acts as the floor.

For creating the roof, we just need to duplicate this box, and move it a bit higher. Holding down the shift key, click on the box to duplicate it in 3D Studio MAX ( 3ds max ). Using the move tool move one of the boxes to a higher position, as shown in the figure.

Rotate and see the new box in the perspective viewport. In the perspective view, click on the wall on which the new box overlaps. Now in the create panel in 3D Studio MAX ( 3ds max ), inside geometry choose compound objects from the roll out.

With the wall selected in the viewport click on Boolean within the compound tools. This displays the Boolean's parameters in 3D Studio MAX ( 3ds max ). Make sure that Subtraction (A-B) is active within the category - operation. This mode lets you subtract the second operand from the first. Here, the first operand is the wall on which we applied the Boolean. We need to choose the second operand (new box we created).

Now click Pick Operand B and click on the new box that we created for constructing the hole, preferably within the perspective viewport in 3D Studio MAX ( 3ds max ). This should create the hole required for the door. See the figures.