The site contains 3 sections where images are placed according to the degree of complexity. You have already noticed that almost all the pictures consist of repeating patterns.
The section "For beginners" contains simple images pleasant for you to look at. Just concentrate on any dot of a pattern and try to divide your stare into two while shifting another eye very carefully onto any dot of the next pattern. When precise lines of a figure blur "wiping off" the image you will feel your sight broadens and penetrates deep into, opening a new space invisible earlier.
The section "For advanced" contains images for which a parallel technique (||) is used. Relax your eyes and just "stare" at a picture as if looking through it. When the vision blurs try to fix this sensation. In few seconds the flat screen before your very eyes will begin to swell giving rise to perception of visual depth.
The section "For aces" contains images that are probable to give you troubles and pleasure. For viewing these images both the parallel and cross techniques (> <) are used. Place a pencil between your eyes and a picture. Look at the tip of the pencil. Then slowly increase distance between the screen and the pencil while bringing the latter near to your eyes. Having reached a right position, you will see a three-dimensional image.