After BBA you are interested to a designer course. There are types of designer courses like interior designing, fashion designing, visual designing etc and it depends alot in which designing you are interested in. 

You can appear for NIFT entrance exam and apply for its UG courses in B.Des (Fashion Design/Leather Design/Accessory Design/Textile Design/Knitwear Design/Fashion Communication).

The maximum age limit is 23 years and its a UG course.

Incase you are looking for a master course then you can do specialization in the area of interest in design field. 

You will have to specify which designer course you are interested in and if you are asking for any specific institute?