There's lots of videos on this kind of stuff on YouTube. But...you build a block in the wooden room in the middle of the spawn. When you leave the room it becomes a custom block. You then go back in the room, select the custom block you want to move, and press start. Go down to set custom block...and pick an option. There are lots to choose from. Movements, fire, water, smoke, factories, conveyors, beamemitters(they power the factories) jump pads, etc.