After clearing a particular entrance exam or the criteria of any counselling, you have to register for same. In counselling you need to fill up your details like roll number of board class and roll number of the entrance exam paper through which your other details like rank and category is verified, you need to provide all the compulsory certificates in the counselling form. After you are done with the details candidate go for choice filling and locking. In choice filling and locking candidate prepare a preference based college list with their respective branch lock it before the last date. 

According to the cutoff your data is checked and you are provided seat in a college according to your preference list.