Hello Himanshu, one's you are done with CET exam, then just register for counseling section CET pune... 

Book - BBA Common Entrance Test (GGSIPU)+ Practice Paper of Arihant

All the best

Hii..! Himanshu there is no such need of registering to colleges individually if you have appeared of CET exam.

what you have to primarily do is register yourself for counselling of CET pune, 2018 then to be eligible for having counselling process done you need to qualify the exam, which is one of the eligibility criteria.  Then, you would be asked to report for allotment of seat and that completely depends upon your discretion whether to accept float or reject the seat alloted to you in the counselling by the process of Centralised Allotment Process (CAS)

for further queries you may refer the link below.  i hope that would serve your query.  Good luck to you..!

https://engineering.careers360.com/articles/mht-cet-counselling 

Registration for admissions are done on the websites of college. Altough entrance is not compulsory for admission in bba in private colleges but many colleges conduct their own entrance exams. You can go for that.