Can someone tell me what to about Gui's please?

 

I'm trying to create a real new Anvil, with other possibilites than the Vanilla's.

 

Let me know what do I exactly have to do. ( What does it need to make a GUI ).

 

Thank you in advance.

I've been using this website and some of the linked ones. They've been very useful.

 

http://jabelarminecraft.blogspot.com/

Thank you very much. I'll take a look when I come back at home