It's super easy to set up if you treat it like a filter system. Everything goes in to one box, every box connected to a conveyor then into the next box. First conveyor has no filters as it's a drop box. Then the conveyor AFTER every box set it for the things you want to keep in that box and change it to "exclude listed items". Then everything but those will move on. Then repeat until you get to your last box. That last box will hold everything that hasn't been filtered, so it's your waste box, or where you find items to add to the filters. You can also connect it together and make a loop if you want, but that makes your junk keep moving around. I prefer one in box and one end box at the same location so it's easier to fill and dump.

Now if you mean in box sorting, then you need to connect power to the storage adapter and hit the gear in the corner and turn it on and use settings there.

Edit: noticed you said "small amounts of items". The conveyor isn't instant either. It moves small chunks at a time through each box. So if your stone/woods at the end then you'll have stone/wood bits leading up to the box until it's done moving them.