When you start Windows 98 for the first time, there is a plain,
teal green background to the screen. You can change it to
a graphical background called wallpaper.
Here's how:
Right-click the desktop, and then click
Properties.
On the Background tab, click an item in the
Wallpaper list.
In the Display list, you can choose to
Center or Tile the image, or
Stretch it to cover the whole screen.