Hi Aully, I just contact the company or the person who posted and ask if they are willing to ship to Canada. If they are, they get either an estimate or the exact amount it will cost for shipping and let me know the amount, which I include in my payment. When I buy things that are 'shipping included' on the board, the seller charges me the additional amount it costs to ship to Canada over and above what they allocated for shipping in the US. Same thing with swaps. I contact the coordinator and either send postage under separate cover or include the cost of postage with my swap package. If you don't already have one, it's a good plan to open a PayPal account, because you can send money to anyone with an e-mail address whether they have PayPal or not. I send postage as a 'gift'now, which is easier and cheaper than any other way I've found. Any questions, don't hesitate to PM me.
Good luck and Happy Quilting!