Wind turbine Blade.

I'm designing a Wind turbine blade

it will consist of 7-8 Planes , an airfoil at each plane , means 8 airfoils with different thickness and maybe different angle of attack's , then Loft between them to form the blade .

How to twist ? will the whole blade will be twisted ? or just an airfoil ?

and how to twist one airfoil ?

and how this will affect the defined angle of attack for each airfoil.?