For this tutorial you are going to need:

20/20

I've used this wonderful picture for this tutorial:

Open this picture in PSP. Choose a colour with the colourpicker. To
enable to colourpicker.......click on the coloured box you
see on the next picture:

After you've clicked, you'll see this window:

With your cursor, move over your picture untill you've found a
colour that you like. Then left-click and you've selected the
colour #9DBDDD.....I've chosen  (as you can see).

Now.......go to image, add borders and apply these settings:

Your picture should look something like this:

Now, chose another colour.........this time I've chosen
#D4DEF7. Again go to image, add borders but this time
use these settings:

And now your image should look like this:

The difficult part is over now (phew)......save this picture
and open it in 20/20. In 20/20 go to image, tile effect
and your background is finished !! As simple as that !!!