Sounds like you are on the eBaydotCOM site for selling.
We're on the eBaydot CA Canadian site right now.
On dotCA you can use Calculated Shipping with Canada Post rates and services as the defaults. Tip: check the options list for Metric measurements and use those rather than the default Imperial which are inaccurate. Canada Post went metric in 1974.
On dotCOM you can only use Flat Rate Shipping, which is fine if you are shipping only to the US or if your items can go LetterMail. However there are at least two rates for every service within Canada and the differences can make or break your profit margin.