Hints & Tips for adding content

Why has this got a blue shaded box behind it?

That's what happens when "Sticky at top of lists" is selected. (Drupal applies a style to such posts, so the style could probably be switched back to a white background if we wanted "Sticky" posts to be sticky but without the background....)

I've used a table to help layout images but why is the table shaded and how can I get rid of this?

It looks like the default style for a table is to shade it grey. This can be removed but takes a couple of additional clicks:

Once the table has been created, put the cursor into one of the cells and "right-click". A menu should appear (like the left hand image below). Select "Table Properties". A dialog box will appear (right hand image).  Select the Advanced tab and enter "layout" in the "Stylesheet Classes" box. In the Table Properties tab you should also set "Border size" to 0 (this hides the lines between the cells). Then press OK.