As the 12th class, the result has been already declared so you must have got the result from the online CBSE site. So, download that result in the form of PDF or image whichever way it is possible and you can upload that document right now. This document is used to verify that whether you have cleared the 12th exam or not and whether you pass the 75% marks criteria. Later during admission to the college, your original documents will be verified.

Make sure you upload the documents before 5th June 2018.

Feel free to ask if you have any more queries. All the best!!