Here are the supplies you need:
Start out by adding color directly to the block either by pressing an ink pad onto it or by coloring on it with your markers. I am showing both ways below.
Next, spritz water onto your inked block. How much will depend on the type of paper you use. For the ink pads I used watercolor paper and on my marker example I used Stampin UP whisper white. I generally spray it 3-4 times. Below is how the block looked after I sprayed it with water. See how the ink beads up.
Then stamp onto your paper with the block and let the ink absorb into your paper
This is a very easy technique to do and your results will vary each time you do it depending on the colors and paper you use. You can combine using markers and ink pads which is what I did on my example below.
Here are the SNSS products that I used on my cards