My father has alzheimer's and he needs a Power of Attorney how do I go about it?

You cannot obtain a Power of Attorney from your father. That must be done voluntarily by a legally competent person. You need to petition the court to be appointed his legal guardian. You should visit your local Family & Probate Court to determine what the requirements are. You will probably need an affidavit from his physician. The court will advise you. If you have a family lawyer you should call and get some advice on how to proceed.