HOW CAN I RESIZE PHOTOGRAPHS WITHOUT DISTORTING THEM I WONDER.....?

A couple of posts ago I said I would re-post this once I had figured out what went wrong with the last one which looked more like a thumbnail. Still a bit confused. Maybe someone has the answer and if you can throw some light on it... please do.

Experimenting with photography is lots of fun and I've got a long way to go. Hope to get some helpful tips.