Hello

Many top B-Schools offer specialisation in various disciplines. For admission to MBA program you will have to appear for entrance exam like CAT, MAT, etc. Many Universities also conduct their own entrance exam.
To prepare for the entrance exam, firstly, you should know about the detailed syllabus and exam pattern.
Top MBA Coaching Institutes are- Career Launcher, IMS Learning Centre, TIME, Bulls Eye, etc. You can join any of the coaching institute.
Good Luck!