To make things easier, several widely-used colors have been given common names. Now, identifying a color by name is equivalent to identifying it by number. Here is a list of predefined color names with color swatches. It's fun to browse the Web for fresh images for your pages. A quick search will turn up a gazillion freebies in the public domain for your use.
Public domain means nobody owns the artwork.
Many Web artists have published pages of their art and placed those artworks in the public domain for use by anyone. Otherwise, when using graphic-image files downloaded from the Internet, bear in mind the possible legal implications. Of course, you can't own information, only the way it's presented. And, U.S. and international copyright treaties allow you to download files from Web pages. However, those U.S. and international rules control how you use the files.