Its full of explanations for almost every method and class..also the workflow of the whole code is described below the code files in the page i linked...so you have created your item, but you need a container to store things in it, and a gui to interact with it. What the code does is exactly that..it creates an item, it creates a container for the item and an associated container screen (your gui), then it gives the item the possibility to access the container and store items within it. Of course the code that does that is a bit long and complicated, but you really need to read it carefully and try to understand it, then ask questions about specific things of the code. You don't expect someone on this forum to write the code for you right?