Thank you so much everyone for all your help, I have a bit of learning to do yet I can see.
Mark thanks especially for the links to the tutorials, I'd somehow managed to miss those.
I shall happily get Fracted now. :-)
Unfortunately you are talking at a level beyond my understanding.
I just grabbed the software and started drawing. I have a workaround at the minute where I draw a circle, give it the characteristics of a wall and send it to the back s…