So say if I wanted to mod upto the current Call I'd duty, is that all done on Xbox 360 RGH's?

I actually want to start Xbox one modding! I have money behind me just need to know how

Okay so I used to go on here like 8 years ago, used to love modding on the 360 on cod, I want to get back into it but where do I start and how do I do it? If anyone can help that would be amazing !