This is what we're going to make:

What you need is:
- PSP8 or PSP9

1. First open a new image with these settings:
Width=75
Height=75
Background colour=Transparent
Image type=16,7 million colours
Then hit OK.

2. Click on your flood fill tool (the little paint bucket) and in the area where it says Materials. Click on the first square in the second box, which is the box for background colour, and select the first option which is called solid. Now click again, but this time on the square, so another box will pop up in the middle of your screen. Pick whatever colour you'd like as the main colour on your background. And after the colour is chosen, click OK. An example of a colour to choose is #C6CDE2. Then right click on the image to fill the image with the colour you have chosen.

3. To add the blinds effect, go to:
effects => texture effects => blinds and apply the following settings:
width: 6
opacity: 15
colour: see below
Horizontal: checked
Light from left/top: checked

The colour you want to select when adding the blinds effect, is a slightly darker shade of colour you chose in step 2. The preview will show how it will look like and you can use that as a guide before clicking ok. An idea would be to hover the cursor over the image and click once, that will select the same colour as you had in step 2. Then click on the colour sample to bring up the colour box, and choose a darker shade by clicking above the current mark. An example of a colour code that would work with the example above is #7484AC.

Your background is now ready, remember to save it.
If you'd like it in different colours, you could use the colourise tool.