Can I put a fire pit on a wooden deck?

Yes, if you stand it on a non-combustible base, such as a concrete, stone or ceramic tile slab clearly larger than the fire pit, to catch heat, sparks and ash. The bowl on a tubular stand is the best fit: it lifts the fire above the surface, so the heat does not reach the boards directly. Keep the fire pit clear of walls and railings, and when you finish, put out the embers and remove the cold ash.