Your university should provide you full access to http://www.JSTOR.org. It is probably the most useful online resource for finding historical sources for just about anything. This is where you should always start and it's where I always start when writing University level papers.

Academic databases such as JSTOR are good. It costs money, but access is free if you're university student. A quick search of "vikings" brings up a lot of results

Google scholar is also useful and entirely free. There seems to be lots of good info on vikings here as well

From the sounds of it, your first stop should probably be Wikipedia, which you probably already know how to use rapidly and can be just as good as a history textbook. Surf through a bit of the Norwegian Resistance Movement and the Vikings until you get a better idea of what interests you. Keep on going until you frame a broad research question that you like, such as: "Why did the vikings convert to Christianity?" or "Why did some Norwegians collaborate with the Germans against their fellow Norwegians?" There's lots of great questions left to answer, so remember that you'll be spending many hours reading and writing about this question and be sure you think it's fun.

At that point, you should take your question and talk to someone about it. If this is an "independent research project," that generally just means you're not doing it as part of a larger class. Most professors should realize that undergrads don't yet have experience doing independent research, and they need to learn how. You should be able to take your question to your advisor. This will give your advisor an opportunity to vet your research question, and it will give you an opportunity to ask him or her how to start researching and get some further guidance. You're paying for this class; you have every right to expect guidance and help along the way.

Your prof might name some books or authors, or maybe guide you to a search engine or database that your university subscribes to. Your advisor will likely be assigning you a grade for this project, so it's best to understand what specific type of research he or she expects from you. It's no good to go surfing on Google scholar if your prof only wants you using sources in your library.

If your advisor really is just cutting you lose (I'd be shocked!), but no worries, there's still trained experts who are paid to help you. Go over to the reference desk of your library (ask for directions at the circulation desk if you need to). Tell them you're working on a research project and that you need help. There should be someone available during regular business hours to get you going, and most university libraries will have a librarian dedicated to supporting humanities research projects like yours. You might even be able to find him or her online and send an email to get you started.

Remember that part of your tuition goes toward paying for librarians and professional researchers (like your prof) to help you learn how to do the things you need to do. In my experience, the more excited you are about the research, the more excited librarians and professors wil be to help. So while /r/AskHistorians is a great place to get some advice and maybe even some clarification as you research, you're better off starting with people closer to home.