Additional director to the board in private limited company

For that you have to file a

Sorry for the error..
To be a director of the company, check if AOA of the company provides for additional director, if not, ammend that.
Then if you don't have DIN apply for the same.

Following documents are require to appointment him as additional director.
Consent in writing to act as Director in
Form DIR-2
Intimation by Director in form DIR-8
Disclosure of Interest in Form MBP- {One thing should be noted MBP-1 should not be dated earlier than date of his/her appointment as Director}. –
However, if there is nothing to disclose on the part of new Director, even then also require to take form MBP-1 from Director. (NIL disclosure is also a disclosure required.
After receiving all the documents from the director:-
Call the Board Meeting.
Pass Resolution for appointment Additional Director.
Issue Letter of Appointment.
File e-form DIR-12 [Along with CT Consent + Letter of Appointment)
File e-form MGT-14 [For disclosure interest in MBP-1]
Now this person will be Additional Director Till AGM of company. If company want to appoint him as director then regularize the person as director in General Meeting by Share holder Resolution. File form DIR-12 for Change in Designation of Director along with ordinary resolution.

FIRST OF ALL CHECK ARTICLE OF ASSOCIATION , WETHER THERE IS THE PROVISION OF THE APPOINTMENT OF ADDITIONAL DIRECTOR, BUT BEFORE APPOINTMENT , FIRST OF ALL AS PER SECTION 152(3), EVERY DIRECTOR SHALL HAVE THE DIN

CONSENT TO ACT AS THE DIRECTOR IN FORM DIR 2

DIR 8 BY DIRECTOR OF THE COMPANY STATING THAT HE IS NOT DISQUALIFIED AS PER SECTION 164(2)

FORM MBP1 DISCLOSURE OF INTREST AS THE DIRECTORS IN OTHER COMPANIES

PASS THE BOARD RESOLUTION FOR APPOINTMENT OF ADDITIONAL DIRECTOR OF THE COMPANY

FILE FORM DIR 12 WITHIN 30 DAYS OF HIS APPOINTMENT

NOW YOU CAN HOLD THE OFFICE AS THE ADDITIONAL DIRECTOR TILL THE AGM OF THE COMPANY. IN AGM REGULARISE SUCH DIRECTOR AS EXECUTIVE OR NON EXECUTIVE DIRECTOR OF THE COMPANY AND PASS ORDANARY RESOLUTION UNDER SPECIAL BUSINESS. FILE FORM DIR 12 WITHIN 30 DAYS OF APPOINTMENT

TO BECOME THE SHAREHOLDER OF THE COMPANY, EITHER TO AQUIRE THE SHARE FROM RIGHT ISSUE OR PRIVATE PLACEMENT OR TRANSFER OF SHARES FORM YOUR LAWS OR SPOUSE.

FOR TRANSFER OF SHARES FORM SH4 NEEDS TO BE FILED AND STAMP DUTY OF .25 PAISE OF EVERY 100 RUPEE.

AND AFTER BECOMING SHAREHOLDER OF THE COMPANY , YOUR NAME IS TO BE ENTERED IN REGISTER OF MEMBER IN FORM MGT 1, FINALLY AFTER THE WHOLE COMPLIANCE YOU WILL BECOME THE SHAREHOLDER AS WELL AS THE MEMBER OF THE COMPANY