background for paragraph text only

[eNGiNe]

A one-off task has hit my desk, and I'll probably have a few questions … this morning's is about applying a background colour.
I've entered three paragraphs, each with less than a line of text, then tried the Shading tool from the Paragraph group to set a background colour. The result is a block of background colour the full width of the page, when what I want is a block of background colour only behind the text.
How do I set the background colour behind the text only? thanks in advance.