I chose to use this huge butterfly as it has a large surface area. Stamps with a larger surface are better for this to work properly.
Spray the stamp while it's on the block with your chosen colour of ink. Don't hold the spray too close otherwise it'll result in too much ink puddling. It might stain your stamp afterwards but that won't do any harm.
Stamp down onto some water colour paper. The result won't be perfect but you're not aiming for perfection anyway.
Let it dry or dry it with a heat tool, then spray some ink into a mixing tray. Use a paintbrush dipped in water to paint the colour into the background. I watered the ink down a bit to make the colour a bit less bright.
Flick on a few ink spots and you're done.
Have fun with your inks, you can do so much more than just spray with them.