Homework Help: Dark matter in our universe

It is huge. If you are starting from scratch, I really don't think there is anything wrong with starting at Wikipedia. http://en.wikipedia.org/wiki/Dark_matter It does have further links.

 

Dark matter is matter that has little to no electromagnetic interaction. There is a known quantity of baryonic matter that is considered to be dark matter but it is a very small percentage, neutrinos are also dark matter, neutralinos (haven't been proven to exist but a strong candidate) and axions (but I don't know much about them).

I did a research paper on dark matter last semester and have to tell you it gets very complex and in the end no one knows because there has not been experimental verification for what dark matter is.
This is a link that was provided by Chronos that really helped me get my research underway.
http://arxiv.org/abs/1201.3942
Good luck and careful not to get sidetracked too much with the quantum physics involved!