in case you didn't know, i think it's when you turn it to the right, it will keep going to 180° so that you can bounce off the wall/ceiling behind you. also, the slider on the rear does absolutely nothing for flash output, it's only to help you in figuring f stop with distance. also, if you're really on the cheap, like me, go to a local craft store and pick up some sheets of that craft foam - i got an sheet of each of white and black with adhesive back and stuck them together and cut them similar to the one seen here:
DIY Reflector-Diffuser and placed some velcro in similar places - works great as a fill flash, i used it on my first "shoot" yesterday (outside, very overcast) and i was really surprised with the results, gave just enough fill to light the peoples faces without looking like i used a flash - the only way you could tell was because one of the guys was wearing glasses and you could barely see the reflection.