What is the JEE Main Counseling process in detail? Do we need to put options for every round? Do we need to get a seat in first round to proceed for next rounds?

Jee mains Counselling procedure is described on josaa official website. U can check there. And choice filling that u are asking for, it is done only once. After that same choice will be same for successive rounds. It is not necessary to get a seat in first round for participation in next round. U will get seat in any round depending upon ur rank and choice filling.