The background of a page can either be a solid color, a picture, or a combination.
The background color of a page is changed using the bgcolor="#??????" option in the <body> tag.
We have provided a sample page to give you a color selector for background colors.
Background pictures are also set in the <body> tag. But they are handled by a different option.
To set a graphic as your background you would include something like <body background="http://www.domain.dom/graphics/bkg00.gif">.
We have provided a sample page to test various background images to see their effect. For this use our interactive page swatch program
Some sources of backgrounds:
The fact that a particular website is listed here is not a measure of recommendation. It is merely illustrative of
the multitude of such sites. In a Google search there is over 500,000 sites devoted to free backgrounds.
It shouldn't be too hard to find some sites to put on your favorites.