Hi Burcu,
Etsy doesn't require you to register as a business, to have a shop on Etsy. But you should look into the Canadian regulations/requirements of running a small, home based business in Ontario, and Toronto.
http://www.cbo-eco.ca/en/index.cfm/starting/how-to-start-a/how-to-start-an-artisan-and-craft-busines...As for shipping - Canada Post will be changing some services and raising parcel rates starting Jan 15th 2018. They haven't posted all the rates yet, just Small Business Prices if you have joined their free Small Business program, and print your labels direct from the CP website.
Here's a link to Etsy's recent post, which gives a little bit of info. on price increases, if you buy Canada Post labels directly from Etsy
https://www.etsy.com/ca/help/article/5975#Q3if you can keep the thickness of your envelope to no more than 2cm or .75" then you can ship as a Light Packet to the USA and International until Jan 15th. For shipping within Canada the cheapest rate is as an Oversized Letter (envelope must not be thicker than 2cm), it has no tracking, and you cannot buy insurance. You can only buy Oversize Letter in person from a post office, or buy stamps and have these on hand, have your own weight scale so that you can figure out your postage yourself.
Starting Jan 15th/2018 Canada Post will be cancelling Light Packet, and you will have to use Small Packet. For Small Packet, thickness is not an issue, but there are 10 different "Zones" for International shipping for Small Packet, so rates will vary.
BEst to ask any future shipping questions on this thread:
https://www.etsy.com/teams/7654/etsy-international/discuss/6779956/page/433