If you have a fire truck are you obligated to put out a fire if you arent a firefighter?

No you are not. If you have a scalpel are you obligated to perform surgery. Again, no you are not. Just because you have a fire truck does not mean that you should or can use it to put out fires. If you do use it then you open yourself up to all kinds of problems. I am a firefighter/driver/pump operator and it takes a lot of training before you learn about firefighting. You can do more harm than good even though your intentions are good. If you are a last resort in the effort to save a life then I might say yes. But if there are trained personnel either paid or volunteer available, then I would let them do it. One thing that we as firefighters have to worry about now is law suits. If you do something wrong someone could sue you for all you have and more. Additionally, if you own a fire truck,in most states you'll need a CDL (Commercial Drivers License) to operate it, as it is no longer an emergency vehicle with exempt plates.
Fire prevention refers to the proactive steps taken to prevent the hazards and destruction that is caused by the fire.