Please help me customizing my desktop!

I wanted to transform the Retro xfwm theme
Into something like this:

, is not terminated but its only a sketch, if only i could apply it on my desktop…

May be some of you are thinking that im trying to collapse my desktop, and may be youre right but lets give a try.

After passing days reading the documentation, not understanding a damn and tuning Ambiance just to look not very good,
im off, I dont know what else to do.

Obviously im not good at CSS and most of my work on computers dont get involved with programming graphics, so please tell me how can I overlay images on everything like above?

My desktop environment is xfce4.
Now i re-found this theme, awsome, now maybe i will progress with ease of pain.

By now I just reached to this:


or this:

Not very convincent at all .