Starter Kit Mod - Need Help - Documentary?

Hey Guys,

I have an idea for a mod which allows the admin to manipulate the inventory for each character spawned the first time on the server. In other words, every person who joins the server for the first time, receives a “Starter Kit” wich can be set up and customized by the admin…stuffed with things like hatchets, stone picks etc. . The best possible output to me would be a customized storage box inside the inventory, which holds all the stuff inside without spamming the slots in the inventory and weighs almost nothing.

My problem is, i have no idea where to start or how to dive into this, because i can’t find any documentation. Can you give me hint where to look for it?

Thank you in advance

Starting to compile just that here.