First you have to register yourself in www.aces.gov.in. Log in and enter the details. You will get the login password in your mail. After that you can login to the site and fill up the registration form with all details and submit the application. Take a print out of the registration form and submit the documents, such as PAN of the applicant, address proof, MOU/partnership deed etc (as applicable)etc. and submit the same to the Jurisdictional Assistant/Deputy Commissioner. Thereafter, the department will issue the certificate if the application is correct in all respect. You may contact the concerned Range Officer for further guidance.