You should start here: http://www.cic.gc.ca/english/immigrate/sponsor/spouse.asp
It provides all the general information on how you can sponsor your husband.
You will most likely be using these forms:
http://www.cic.gc.ca/english/information/applications/fc.asp
This is for what is called the 'outland' application. Such applications are processed outside of Canada, in the visa office responsible for your husband's country.
There is also the option of an 'inland' application - those are processed inside Canada and are intended for those who already have a status in Canada (are there on a study or work permit for example), which is why they tend to take longer than outland applications. Be advised that even if your husband is IN Canada when you apply, you can still choose to do an outland application.
You can only sponsor a spouse or a common-law partner. To sponsor a common-law partner, you need to have lived with them for at least 1 year and be able to prove it. If you haven't lived together, then it's probably best to marry first and apply after that. There is also the conjugal partner option, but that is rarely used.
When applying, your husband will need to do a medical examination and obtain police certificates from every country country he lived in for 6 months or more since turning 18. If he's from the US, he will also need state police certificates from every state he lived in for 6 or more months.
Aside from that, you will also have to submit evidence to show you have been in a genuine relationship - anything that shows how your relationship developed and how you've kept in touch. Phone bills, cards, mail sent to you and him at same address, letters from family/friends, chat logs... it depends on your situation.
There are no financial requirements to be a sponsor, but you have to not be bankrupt or receiving social assistance.
There are two steps to an application (assuming you're doing an outland one): the sponsorship application and application for permanent residence. You have to send in everything at the same time (including all the supporting documents). You send it all to Mississauga - they approve the sponsorship and forward it to the visa office which finished the processing. If an interview of the applicant (your husband) is required, it will be held at the visa office.
I'd suggest you look over the forms (especially the guides) and take a while to familiarize yourself with them. After that, come back if you have more specific questions.
If you are in Quebec and intend to have your husband come to Quebec when he immigrates, there is an additional step that residents of Quebec have to do. It's all in the forms, just keep an eyes out for it.
