i want to join icsi after 12 std,how to join and what preparation i have to do for joining,parallel what i can do along with icsi to uplift

what i can do after 12 std commerce to join icsi,when i can join,where i can get addmission,what is the procedure,why icsi is important,what i can study parallel with isci course,what is the tenure of course,is it a fulltime course,which college i can find in mumbai,what is the course fees,guide me