Hi guys, I'm a newbie into the world wide web. I'm planning to design a website but i'm stomped upon an issue regarding to the URL of my site. I'm not sure how the legal stuff works when it comes to naming the websites. But I wanna know, for example, if someone else already has a website called www.abc.com, and I wanna name my website called www.abc.ca, can I get sued by the other guy?

Not if you use all of your own material and own design. Your Domain name does not have to have anything to do with your Business Name.