Since you said private college, I'm thinking whether your college comes under approved post-secondary colleges. What I have heard is that students studying in private colleges are not even allowed to apply for off-campus work permit, so post-graduate would definitely not be a possibility. But in case your college is approved post-secondary college, then you need proof of your completing your program (a final transcript or a graduation letter). You also have to complete the application form IMM5710E and have a copy of your passport scanned with sate of issue, expiry, your name page plus any pages with stamp that should definitely have the most recent entry to Canada stamp. If you are applying online, you need all these scanned plus you need to attach a digital photo and need a checklist number which can be a pain. If you are applying by mail, you don't need photo or checklist number, instead you will need a printed document checklist. You should apply for this permit within 90 days of your receiving final grades.