I want to change my name/surname legally

Just get married ... Seriously speaking, you have to consult a lawyer and costs depends on the rate of the lawyer that you're going to hire. For starters - find free legal consultation services (usually offered by NGOs) to save you on initial fees.

In the Philippines you need a judicial order to do this. See here: http://en.wikipedia.org/wiki/Name_change#Philippines If you need to have records changed because of a clerical error, this can be done without a judicial order by filing a petition. All the information you are likely to need can be found here: http://www.citizenservices.com.ph/blog/view/id/153

why would you want to change name or username? What did your father did to you anyway that you hate him?

I don't think that it is easy to do that. You need to go to court to be able to do that and present the reason why you need to have your name change. Might as well consult with a lawyer.

I am not very fond of my father and I don't want to have his last name. I figured, if I want to get rid of it, all I have to is get married. I don't know what it takes to change your name in my country. I do like my name, but not my last name. Hopefully by now, you have it all figured out.

Hi, I don't know how to change name or surname legally. But I just want to ask you why do you want to change name and surname?

Eppie is right. That was what I about to say. Haha. I think that's the cheapest and easiest way to change your surname. But about the name? I think it will cost you a lot. And you have to change the files that had your name before. Good luck in changing your name. BTW, if I would change my name, I would choose, Dianne or Daphne. Nothing. I just find it beautiful. :)