Modifying a spacing of cells and background of a notebook

A simple question: How do I reduce this spacing and how to change the background?

I think it is in the Options Inspector, but I cannot find the exact location to make the modification.

As for the background, how could I add images like this:

• Which Stylesheet are you using in the first example? Is that Standard Report? – Mr.Wizard Jul 20 '16 at 12:44
• I believe the second part of your question is a duplicate of (6961). Also related: (6318) – Mr.Wizard Jul 20 '16 at 12:59
• @Mr.Wizard Yes this is the stylesheet. – LCarvalho Jul 20 '16 at 13:28
• I will check these links... – LCarvalho Jul 20 '16 at 13:30

The gap in the first example may be controlled with the Option CellFrameMargins. This can be done for one cell at a time or by creating a custom Style Sheet. Either is assisted by use of the Option Inspector.
The result of changing its value to -5: