[1.7.10] Container - ItemContainer. Create a Backpack.

Hello, my name is Kenzo and I'm 18 years old, I have been trying to create a Item container, like a backpack, but just can hold specific items, but, I can't create the Item container, all what I had successfuly was showing the gui.png, just that, so, can please you help-me? with tutorials sites, videos, all videos I found was to 1.11 + but I want to create to 1.7.10, so please, help-me, I'm really sad to can't create this. And how the tutorials are english is more dificulty to me, bcs english is not my mother language. but you can use english normal, the videos, and tutorials websites can be english to, I really need a hint, something. thanks for reading.