Another way to do it is bank draft.
Is this your first session?
If so,you may have to go to info service to register and get your student ID,and then they will tell u how much you need to pay to UO.Then go to your bank with the invoice letter from info service,ask teller to make a bank draft which is payable to Univeristy of Ottawa.Bring draft back and hand in to the info service.
Probably the bank draft will cost 5-6 CAD.
Good luck.
you can also check the information you need on the website of OU