I am very coward would like to be bold

My name is suzane from Nepal. I am married and has got a beautiful daughter. Since my childhood I am very coward I am graduated from London University but I cannot work commandingly as I am working as manager in private organization. I have pleasant personality and good education but my cowardness won't let go a head. My boss always tells me that you are not capable to handle managerial task. They warn me if I do not be bold & active they going to fire me from the job.

Please advise me how can I get improved and show miracle to the back bitter