Install Camscanner(Application) on your phone. So when you take the photo of your 12th standard marksheet, it automatically gets converted to PDF format. And easier for you to upload. Keep in mind the size of the document. There's generally a limit.

Camscanner naamka app phone pe install keejiye, usmese jab aap tasveer lenge, woh Apne aap PDF me ban jaega. Sirf, PDF Ka size aapko dekhna padega. Ek size ke upar Nahi chalega.