Hello Azhar, 

You have to first wait for the merit list to be released then they have to take out the printout of the counselling form available on their official site and fill the required slots as per their requirement 

Here i am sharing a link with you which help you in getting complete details of the counselling procedure.

hope it will help you in clearing your doubts 

https://engineering.careers360.com/articles/assam-cee-counselling