Hi, and welcome to the forum.

You should be able to find out what you need here: Sponsoring your family: Spouses and dependent children. It's the official website for Citizenship and Immigration Canada, and they seem to indicate that you will need to get visas for your husband and children. They require the usual round of medical exams and police checks, but since you are a Canadian citizen returning to Canada, you should be able to sponsor the whole lot.

If you want to move in August, you'd best get a move on. These visa things can take a few months to tackle - if only for the need to secure all the proper documents. Good luck with the process - and keep us posted how it goes.
Cheers,
Bev