Help please!! Can anyone tell me how to construct this image please. (without using autotrace). I'm sure there's a way of adding an effect to a bitmap?

I am not aware of an automagical way to do that in CorelDRAW.

It's certainly the sort of thing that a macro could be written to do.

If it's just the image you show - and not the same idea extrapolated to something much more complicated - then I can do it manually without too much trouble using Snap to Grid and Space-bar-while-dragging to drop multiple copies of a shape.

I created a Symbol for each different size of dot (except for the one in the center). So, after laying it out, it's easy to tweak one particular dot size, and have that change applied to each instance of that Symbol.