Firstly buying from a seller here in the UK, you first must check that they post to Canada, as not everyone sells internationally.
Then, the forms of payment eBay now accept will be listed on those listings, and they include a range of credit cards, debit cards, PayPal and sometimes Klarna Payments allowed.
Two forms available for you to buy and pay for items on eBay is either sign up for a credit card, or open a PayPal account, add money into it from your bank / checking account, and use PayPal as a form of payment.
@cascodlia