The background color of a Web document affects exactly that...the background color. Changing the background color of a Web document requires the insertion of the bgcolor=" " tag within the open body tag <body> illustrated in the HTML Structure section of this site.
The open body tag could be modified as follows:
from <body> to <body bgcolor="black">
You can choose from the 16 standard Windows colors: black, white, red, green, blue, yellow, magenta, cyan, purple, gray, lime, maroon, navy, olive, silver, and teal.
Note: If the text color is the same as the background color the text within that document will not be seen.