I have saved a copy of the default floor as a new prop and turned it 90 degrees and renamed it as background as well as a copy of the floor as ground.

I texture this for some scenes as background and ground/soil.

Sometimes I manage to do this and sometimes it just don't work. I only save a straight image. No bump or more. I still do not understand why I do what in what following order.

Where can I get a tutorial on texturing basic flat stuff or a simple thing?
I also noticed that the Tree props that I have downloaded from somewhere is actualy a photograph of a tree posted on a transparent background or ..... posted on a transparent flat background polygon.

It sounds like you are trying to make a backdrop along with a ground? If so there are much simplier ways :)

RDNA has "Infinity Cove" and Daz3D has "Cyclorama". They are curved planes that have a back and a ground that are one prop. They are props that use images that are specifically mapped for the template. And the nice thing about these is that they interact with the figures, and other props and lighting so you get more realistic looking shadows etc.

Quote - I also noticed that the Tree props that I have downloaded from somewhere is actualy a photograph of a tree posted on a transparent background or ..... posted on a transparent flat background polygon.

Those "tree props" are poster boards, not really tree props.  I don't know why people upload them as "tree props" because that is not what they are.

RDNA and Daz have tons of real foliage props that are actually props and not "trees on a background image."  Plus you can find some free ones around the poser sites too.  Planit3D has some free trees and plants.

If you need links to other free sites, let me know. Either me or someone else will be able to post more links for you.

Also look in the freestuff at 3dcommune.  Several "real" plants and trees have
been posted there recently.