Hey Abdulla, once after the ranks are given the board/university call all the qualified candidates according to their ranks for certificate verification for category and fee reimbursement purpose.Before that you need to make a payment of 1200/- if OC or 600/- if SC/ST.After the successful payment the board sends you login details for webcounselling which happens after the certificate verifications.The counselling hppens in 3 rounds.if in the 1st round you didn't get the college you liked or that you mentioned while web counselling college options you can go for the further rounds.If you got the seat in the college you want then download the allotment order and submit that & required documents in respective college you are alloted.They confirm your seat at their college to the board and  inform you about college related details.

All the best!