Step 1 is to hire a lawyer experienced in guardianship law. I see that you're posting from Texas, and I practice in guardianship law in the Dallas / Fort Worth area, but would be happy to visit with you whether you are in this area or not.
I'll assume, for the sake of this answer, that when you say "take over his money," you mean manage his finances in order to provide for his welfare, at a time when your father is no longer capable of doing so. If your father is truly incapacitated, he is beyond the help of estate planning and you need to obtain guardianship of him in order to look after not only his finances, but his personal well-being as well. Obtaining guardianship is not something that you can do by yourself. This is not to say that you are incapable of grasping the idea -- the Court literally will not let you proceed without hiring an attorney.
My office's website www.jbrianthomas.com, includes some helpful basic information regarding guardianships, and I would encourage you to review it or any of the multitude of resources out there regarding Texas guardianship law. Best of luck.
