Hii RIYA
Seems you are very tensed related to counselling. I guess you shouldn't be. Just hope for the best.
Coming to your question. There is no such choice like first, second or third during counselling.
Suppose there are 6 colleges who have taken part in counselling and you are a higher rank student then the authority will verbally ask you to choose your college on the basis of your interest.
And suppose you are a lower rank student and  a stage comes in counselling where only 3 colleges left so you have to choose from these 3 colleges on the basis of your interest.

All the best
Feel free to ask for any query :)