smart1, why should you have four hands? Like zzxxee, you are asking an elementary question instead of learning just a little bit of the fundamentals of evolution first.
Evolution has no aim or plan, including giving you four hands. It comes about by random mutation of the genetic code that is passed on from one generation to the next. Most such mutations will be unviable and, by natural selection, will disappear, some will be neutral and be carried as passengers. A very few will be advantageous and move the evolution process on one notch. But there is no plan.
One day a human being might be born, by chance, with four hands - astronomically improbable but let's just look at the principle. If that fellow has such an advantage over the rest of us that he lives longer and breeds more (again unlikely in our society) then he'll have more offspring who will have more offspring and so on until four-handed people will take over the species.
But that random change has to happen first. Evolution has no plan.
Your 'If evolution was fact....' is out of date. Evolution is, and has been for a long time, an established scientific principle, challenged only by the religious and the uninformed.