Here is an exploded view. Open the Front panel and you will see a red knob with instructions by it. Press and hold down when you turn it to pilot. The pilot is located down and to your right ( where you light it) hold for 10 seconds then turn to on. The heater is ready for use.
http://www.poolcenter.com/parts_heaters_laars_markv_pg2_poolstor.htm