Admission is through CAT exam in FMS.
Selection to the FMS MBA FT course will be based on Personal interview, Group discussion and CAT score
Shortlisted candidates are then called for a Group discussion and Personal interview/Extempore round.
The final selection is based on the cumulative performance of the candidate in the CAT Score as well as the group discussion and personal interview round.

Last year the weight age to all rounds were:

CAT-85%

PI-10%

Extempore- 5%

Rest criteria you can go through in the link below:

FMS admission process
FMS applications start in the month of November. Till then you can check for the updates the above site.
Good luck.