How many marks required in neet UG 2018 by UR candidate in andrapradesh to get free MBBS SEAT IN PRIVATE COLLEGE ?

First of all, you need to understand that the concept of free seat is incorrect in the literal sense. The college will charge you a nominal amount of fees.
Since you belong to GENERAL CATEGORY, understand the fact that a lot depends on the level of difficulty of the question paper and how many students end up performing well.
A score above 500 should help you get what you want.

Hey ,
For admission private college you should clear the cut off or atleast score marks 250+ . But there's no process or rules where you can get free seat or admission in any private medical college whether it's in Ap or overall india . Sorry to disappoint you...