Power of Attorney forms can be found locally or online. There are various levels of power of attorney out there. Some are limited to just certain areas, and others broaden the areas.
Power of attorney is a great tool that creates an avenue for someone to act on someone's behalf under various circumstances....again...very broad in scope.
You can file a Power of Attorney with your local court clerk, but in many areas it is not required that you file. Simply having the document will work. Such as if someone has given you the Power of Attorney to act on their behalf for medical issues....You can present the Power of Attorney document to the healthcare provider and that is usually sufficient.