Picture of that page. You'll have to zoom in or whatever.
How it works is you give chacha up to 5 herbs (or any item on that list), then he'll convert them to one of the Rank B items based on the color smoke he is puffing when you signal him. Then you'll get an equivalent amount of item from that smoke. Then you do it again with those items, and it'll drop down a rank to C. Then again to D. Then again to E. then again to F.
For example if you are going for Max Potion. You can just quickly signal him after giving him items from rank a through e no matter what color smoke shows. Then when dropping to rank F you'll wait for green smoke.
Sounds confusing, and my explanation sucks, but really it's simple. The only problem is you have to level the mask to get the higher ranks. Feeding Chacha well done steak speeds it up.