There will be link coming for recheck and then re-evaluate ,first you have to opt for recheck than they will send you the sheet than you can check whether any questions is unchecked or not or any other discrepancy is there, if there than you can re evaluate.Keep checking the site the link will come soon.

Hi dear,
             The notification for Rechecking of 10+2 paper sheets will soon be live by CBSE board. You can go to cbse.nic.in for all the detailed information. In Rechecking you have to Select the Paper name and then pay the amount to CBSE for Rechecking.
If you are applying for Re-Checking, your best marks out of the two will be considered.
For Example You got 75 marks in English paper and if you apply for rechecking and your marks increased to 80. Then the highest marks ir the best marks ie 80 marks will be taken into consideration while providing your DMC by CBSE board.

Rechecking: Rechecking is verification of marks or Recounting of your marks from the very first page of your answer sheet booklet.Its check calculation mistakes only.
It also checks whether your all answers are reevaluated not checked or not.

All the best