Yes, add spinach to the blender and then fill to the top with water. It makes about 3 days worth. It is only good for that long as well (it starts to really get gross after that, it should only be taken fresh).
Green Drink really helps to PREVENT psoriasis. It took about six months for my existing psoriasis to completely heal. Also, It's very important that you do all three steps 1) Green Drink 2) Moisturize 3) Remove Irritants. If I just do the green drink, it's not as effective. I find that the dust mites are a huge problem for me and if I don't wash my linens and spray then I get small outbreaks.
My scalp was extremely tricky. Even with green drink i had bad outbreaks. I found out that the primary cause was the hair spray I was using. I switched to Fiber by Crew. I also started using conditioner called BED HEAD MOISTURE MANIAC CONDITIONER. Oh man, I have zero scalp problems now and it's wonderful. I only use one soap, BiorE Blemish Fighting Ice Facial Cleanser, on my face, hair (i mix it with the conditioner), and body. Just be aware of what your putting on your body that can be an irritant.