Which version of Vue 8? Below Complete, you only have one possibility: raytraced dof. From Complete and up, you can use Hybrid blur.
Raytraced blur is more accurate, but creates a lot of noise artefacts that can only be eliminated with a lot, and I mean a lot of anti aliasing.
Hybrid is between 2D and 3D blur, less accurate, but requires standard AA levels. This one works in passes after the render is complete.
For both methods, you first need to set up your camera for DOF, and the process is the same:
With your camera selected, choose a target object in the object properties panel ( target icon).
Once this is done, choose the amount of blur you want, minimum 10%, otherwise the effect might not be visible, unless the target object is very close to the camera.
You will notice 2 planes in the camera's field of view:  what's inside the planes is in focus.
Next, just tick the Depth of field box in the render options, and then choose either raytraced or Hybrid. If you choose Hybrid, go for 3 passes minimum. Personally, I always go for 4.