How can i update my name on SSC marksheet ?

You have to approach your board of education for this correction and apply for it. You will have to provide your enrolment number or student ID number and other details so that they can dig out the correct credentials in your respect from their records. So please apply in person or by post for the same. Check if there is some provision in the website of the education board for such corrections. As you did your SSC in 2006 and about 14 years have passed so the education board may also show its inability to get so old a record. In that case you will have to go for legal affidavit in support of your correct name by producing the other documents where it is correct. Please take the help of a lawyer who will prepare an affidavit accordingly for the same and it has to be signed by you in presence of a court magistrate under his seal. You may also go for publishing this information in the local newspaper and apply for gazette notification. Please note that all the supporting documents where your name is spelt correctly would become an annexe to the affidavit and whenever you go for a document verification or interview all these would have to be presented in support of the mistake that had occurred in the mark sheet.

Now you please check in other documents like Aadhar card or PAN card or Voter card or other educational qualifications as what is your correct name there. Take those documents and make a copy so that it can be attached with the affidavit as support to your claim. Does your mark sheet contains father's or mother's name. If it is so then that would be a valuable link to establish your identity for that mark sheet.

As you have noted this thing after such a long gap, the process is going to be a bit cumbersome but take the advice of a lawyer who have dealt in similar cases and can share their experience in your case.

There are two ways for that.
The first method is to approach the tenth board through the school you studied. You have to submit an application stating that there is a mistake in your SSC certificate and correction is to be done. You have to attach the required proof about your full name. Aadhaar card or PAN Card will do that. You require your birth certificate also. In that, your father's name will also be there and your surname also will be there. You have to pay the required fee also. Once you apply to your school they will verify the details and forward it to the board for necessary corrections. The board will do the needful and again send back to the school and you can collect it. They can't reject your request but sometimes they delay abnormally saying that they are not able to trace the record. But sometimes they do it normally. I passed my SSC in 1972. In 2001 I lost my original SSC book. Then I have applied for a duplicate original through school. Even it was 29 years later, they could do the needful and gave me the certificate in about 30 days.
The second option is to go for a legal affidavit. In this document, it will be legally expressed that the name in your SSC record is yours only. You have to contact a good known lawyer who is familiar with the process and he will guide you and see that needful will be done. This will be fast and the total proceedings may be over by 10 days or so.
Please follow the process as mentioned above and your work will be over. Don't lose another chance and I wish you all the best.

The best way would be to approach the Board relating to omission of your surname. Write an application addressed to the secretary of the Board indicating the nature of lapses from their ends. The same application needs to forwarded from the Principal of your school. He may verify the same through admission- register if there is anomaly in respect of surname during the process of admission. If your name accompanied with the surname in the admission register, it is definitely the lapse of the board and the Principal would put his remark in the application.
In support of your claim relating to surname, you may attach photocopies of Aadhar Card, Voter ID card or any other related documents.,
Enclose your application along with the photocopies of the documents mentioned above coupled with demand - draft of requisite amount needed to get the same thing done. Send the application to the appropriate authority through the registered post along with an acknowledgment to be attached with the envelope . Keep the acknowledgment intact once you receive it from the office of the board as a proof of your initiatives. Though there may be some delay in the process, you are sure to get the duplicate certificate with the due correction.
The other process is to approach the lawyer of the rotary court in order to secure the affidavit finally released by the magistrate.