How do we choose a room if we want only 2 people or 3 people ?

The room allocation in the first year is random. You cannot make a choice for room-mates or for the seater rooms in the first year.

The rooms will be alloted randomly in first year but from second year you can choose where you want to stay. So for first year you dont have a choice for selecting room

First year students are not allowed to choose 2, 3 or 4 sharing rooms. Rooms are allotted on random basis however students may choose room for second year.