Could you please clarify how should I make up with my Qadha Fasts for all these years ? Also I want to start fasting for my Qadha Fasts. What intention (Niyyat) should Say ? As this is the month of Rabbil ul Sani but my Fast is for Ramadan? Also is it Wajjb Qurbatan or Just qurbatan illlah?

You would make the niyyat of Wajib qadha

If it has been more than a year, then you must feed one person per fast in addition to the qadha fast or the equivalent in cash which is used to feed someone.