You've found step one - this site. That's where I started. I read as much as I could.
in my opinion - the best book to start with is The Explosive Child.
How old are your kids?
I also got a lot of help through the school system. In fact that's where difficult child gets most of his services now - even his psychiatrist and therapy is arranged through the school and at the school.
I'm not familiar with Canada, however. Someone will be along soon who can help you more with those specifics.
Welcome to the board.
Linda