So, in answer to my own dumb questions and, YES, after reading the relevant parts of the manual and fiddling about...
The most useful commands are found by scrolling into the top of the screen where the 'scroll' showing the height and distance factors. A menu pops down offer all sorts of goodies, including generate random map, saving, and heading back to the main menu (ie. exit)
Once again (as with the demos) I find myself passing from a stage of disorientation and frustration in that the game doesn't have an immediate 'Mac-like' intuitive (some might say 'moron-proof') feel to realising the thrill of its depth and potential.
By using the menu(s) that drop down, you can add hills by choosing that option, clicking on the centre point of the rise and scrolling the mouse left or right (or forward). I've done this both before and after creating rivers. It does not change the level of the river (but does limit the line of the hill).
Thank you all for your help. Any of you who want cartoons in uniform, PM me a photo and I'll see what I can rattle off.
Ta.