You have two choices.. one get married in Greece.. probably the easiest way.
Or two.. get a Travel Visa to Canada and get married there. Ofcourse you would have to prove that you have ties to Greece and that you would be returning to Greece. Job letters, education, bank accounts etc. Also if they somehow found out that your purpose of going to Canada was for marriage they might refuse the travel visa as they would suspect that you wouldn't return to your home country.
After your marriage, you can apply for outland spousal sponsorship and make sure you have lots of proof of your relationship, travel itineraries, pictures, emails, letters, cards, receipts anything that ties you two together as a couple.
If you have any detailed questions feel free to ask.. this forum is full of ppl with lots of experience..
Good luck!
