In MS-DOS 6.22, to add colors to characters, you can use the `COLOR` command. The command format is `COLOR [attr]`, where `attr` is a combination of a background color and a foreground color. For example, to make the characters red on a black background, you can use `COLOR 40` (where 4 is the foreground color code for red and 0 is the background color code for black). To make the characters green on a black background, you can use `COLOR 20` (where 2 is the foreground color code for green and 0 is the background color code for black).

