Dear Shubhadip,
Being introvert or extrovert is natural personality trait. Therefore, there is no need to change it forcefully. There is no evidence that shows that extroverts have edge over introverts. You may be introvert but do not be inscrutable.
Secondly, have you taken any scientific psychological test that showed that you are introvert? Who has verified validity, reliability and credibility of the test?
Thirdly, if someone has given a feedback that you are introvert then you may develop your better networking skills. Leaders demonstrate outspokenness. Their communication is characterised by directness in manner or speech. Therefore, be communicative. When I recommend you to be communicative, please note that I do not mean to say that you need to improve communication skills. You may have good communication skills but what is the use of those skills if person does not use them? Communicativeness demands being proactive and responding to the communication in timely manner.
Fourthly, please do not mistake outspokenness with talkativeness. Chatterboxes are introverts too. What we communicate should be meaningful, to the point and with supporting examples. To make your communication meaningful, improve your listening skills as well as questioning skills. In fact if you ask questions then people will be forced to give reply. Please note that people like those who listen to them! Listening others does not mean accepting other person's views. Do not contradict or come up with counter argument instantly. Put your opposing views without offending other party.
Next thing is not being stingy with the words. Many people prefer to communicate tersely. However, terseness mars the spirit of their communication.
Lastly, people become introvert because they have nothing to say. Therefore, improve your reading. Read editorials and centre page essays of the newspaper. Discuss the contents with your friends and family members. This will improve your confidence.
All the best!
Dinesh Divekar