1. We will work with a flower. So, please save my image.

2. Open start.jpg and save it as *.psd (File-->Save As...)

3. Set white as a foreground color.

4. In the Tool palette choose Brush. Then click on the Brushes menu (top right corner of your workspace). Use my settings:
Brush: Starburst small.
Set the diameter to30-33px.
Set the Spacing to 260-270%.

Use 100% of the Flow.