Deriving f(x)=a(x-h)2+k From the quadratic function f(x)=ax2+bx +c?

Why do I need this first? I just want to know all about deriving function. Of how to get the answer on that and the solution as well.
So please I am the one in here who's asking for your help!
And to not the one who is interrogating.
GET IT!!!???