For change of name you have to prepare an affidavit containing both the names and to conclude with the name to be known by henceforth, get it notarised and along with the affidavit, apply with further necessary documents for getting it published in the government gazette.
Get the copies of the said publication and keep it in your possession always and start using the new name in all your correspondences after that. The names in the educational certificates cannot be changed however you can apply for change of name in the aadhar, pan and passport etc.