Lots of shade and a lot of Hosta's. It really depends on the type of Hosta you are planting. There are several species in this photo. First, you will need to figure out which Hosta's you want to plant and then I would google that specific species to see how big they get so you know how far to plant them. Unfortuately, there isn't an exact design to tell you how to achieve this look. Obviously there are other plants mixed in this area to give it texture, but each "section" of Hosta has about 4-6 of each plant in the area. Group the Hosta's together with one species then move on to the next section, planting several in each section. I hope that helps, let me know if you have further questions.

Never put weed barrier/fabric under mulch. Turns out to be a mess in the long run.