[Kwant] Please suggest documentation to learn theory needed for Kwant..

Dear All, I request you all to suggest some EASY-TO-START material/theory for understanding the concepts behind Kwant. I need to learn the basics before starting Kwant. I would be glad if you could provide any ppts. I want to feel theoretically confident before starting Kwant. Regards, -- *Dr. Siddheshwar chopra,* *M.Sc., Ph.D (Physics)Assistant Professor (Physics),* *Amity University, Noida, India.*