I'm trying to find either a website or a good book that explains the
details of the components of a gasoline powered marine inboard engine
for a "mechanically challenged" boater. Need to understand filters,
separators, fuel pumps and carburators, valves, etc.
Thanks...

"How Boat Things Work" by Charlie Wing.
Brand new, just out, probably on Amazon if not in your marine store or book
store yet.

It won't give you enough detail to help you rebuild anything, but it will let
you understand what the major pieces are and how they relate to one another.