You are already a Canadian citizen. You do not have to apply for citizenship, but merely proof of citizenship. Once you have proof of citizenship, you can get a Canadian Passport and travel to Canada.
Your children are also Canadian citizens. They can apply for the same documents, though you should get yours first, so you can prove their citizenship by descent.
Your spouse is not a Canadian citizen, unless they were born in Canada, or have a Canadian parent. They would have to be sponsored for permanent residence in order to live in Canada.