Oh there's no need for a tutorial for soft-shadows, I'll explain it briefly.
- You can find the soft-shadows setting in the sunlight-node.
- The radius of the soft-shadows determines how soft the edges of the shadows will be.
Also, when light-occluding objects/edges are far away from the surface, lower soft-shadow-radius is needed for soft edges.
Is the object/edge close to the surface, higher soft-shadow radius is needed for the same soft edges.
This all depends heavily on the nature of your scene. So there's no golden rule.
Therefore my guess of a radius of 6 is no more than just a guess
- The softshadow samples determine how accurate the soft shadow will be rendered. Too low amount will result in speckled shadows. Too high increases rendertimes.
This is basically it. If you need any help then just let me/us know.
Martin