How can i file for child support against my father if I am 25?

You have no right to do that.  Child support is determined by a statuory algebraic formula which considers the parents' net incomes and how much time each spend with a child.  You are not a parent, so not entitled.  Under only limited circumstances is child support awarded after a child reaches majority and graduated from school- say 19 years old.  Parents of an incapacitated child have an equal duty to provide for an adult child.  Family Code § 3910.