This is the fun part, before you have to worry about visas and stuff. This is a Bureau of Educational and Cultural Affairs website for students from other countries wanting to study in the US. It has information on American Post-Secondary institutions, funding, and also visas and stuff. As well, there is a link for established Scholars to get information. Unless you know exactly where you want to go, this is a good starting point if you think you'd like to study in the States.
Studying in the USA: Department of State
This is one of the possible starting points for chasing around the US Government websites to find everything you need to know about foreign students working or studying in the States. I've tried to list all of the sites that you might need, but it's possible you'll have to do a little follow-through on your own. They're quite good about telling you where you need to go for a piece of information, but sometimes they don't provide a link, which is maddening, so I've tried to do that finding for you.
US Citizenship and Immigration Services: Student Visas
This is another place to start your quest for visa information. This is the basic, step-by-step information about actually getting a visa so you cn study in the States, whereas the Department of State site above has more of an overview of immigration side of being foreign student in the US.
Immigration and Customs Enforcement: Student and Exchange Visitors
This is a step-by-step list of all the things you'll need to do before you can settle down as a student in the US. From applying for a visa to employment, this will lead you through the process and it has some helpful links to other departments and bureaus at the bottom. The only problem is that it does use a lot of jargon, and some of the links (mostly the very jargon-y ones) are meant for the school you'll be attending, not for you. Fortunately, if your school is an approved place for foreign students to study, chances are that they'll know all the things you have to do, so it's just while you're still deciding whether or where to go that you might want to refer to this.
How do I get a Work Permit?
This is about work permits for the US in general. As far as I know, after chasing through zillions of Department of State and Department of Homeland Security websites, there is no detailed page on getting a specifically student work permit meant for students to refer to (what there is is so full of form numbers and abbreviations that you probably need a special degree to understand it. I think you have to do the whole thing through the school you're registered at (which is nice, because it most likely means less for you to worry about). But since you might want to have some idea of the process, I've provided this link.
Websites of US Embassies, Consulates, and Diplomatic Missions
Inevitably, you'll need to contact the nearest consulate or the embassy, because you'll need to talk to them about getting your visa. Scroll down to "The Americas", and there are the links you need (double-click to use them, single-clicking doesn't seem to work). The US Embassy is of course in Ottawa, and there are Consular Offices in Toronto, Montreal, Winnipeg, Calgary, and Vancouver, as well as "Virtual Consulates" in all three Territories. The Consulate in Toronto and the Embassy can be very hard to get hold of by phone, so start a week or two before you absolutely must get hold of them, just in case.
Study in the US
This is the closest thing you'll find to a student information portal, and it is useful, but none of the official stuff is obviously linked to this site. This is more the academic and cultural (and definitely the PR) side of studying in the States, for example there is information on driving in the US, making international phone calls, and links to many resources about the schools in the US and so on, and well as ESL programs and even some English-language practice games!
Travel and Tourism sites for the 50 States and US Territories
I'm strongly in favour of visiting tourism websites, even if you aren't going somewhere as a tourist. Yes, they are often tacky and overly commercial, but sometimes they tell you very useful or cool stuff that you wouldn't otherwise know, and they're always a good way to get a map of somewhere without buying one. The US doesn't have one tourist website, you have to go to each state seperately, but it's worthwhile, and you will learn all sorts of things about the state your chosen school is in that you'll never learn from the school website.