ISC provides you opportunity to earn by posting previous years question papers. The section you ate searching for is Post Exam Paper. The URL to that page is http://www.indiastudychannel.com/question-papers/PostExamPaper.aspx
Follow the link and post question paper with required details and description. According to ISC, it better to post the question paper as text, which will give you the headache of typing the entire question paper. However you can choose another method instead. You can upload a scanned copy of the question paper as an attachment. For this, go to the URL and give sufficient details and mark the option "I want to add attachments". On the next page add the attachment and submit the question paper. I believe these two are the possible methods. Taking a photo of the question paper and uploading it as an image may not be acceptable.
Hope you get necessary information about the issue.