Luckily for you I am a huge 40K fan. Here are a few links to get you introduced
http://www.criticalhit.co.uk/content/view/18/44/
http://www.redelf.h1.ru/w40k_astartes.html (by the way I collect Mortifactors)
I also visit a forum devoted to it every day
http://www.warseer.com/forums/index.php?
There are plenty of people there who could help you out, although you can't start a new thread till you've posted 5 times. I could start the thread for you if you want.
Later this year a trilogy starts detailing the Horus Heresy, which is pretty much the dfining event of 40K after the great crusade. No one can say at the moment how good it will be but we have long been looking forward to it. I have lots of other links but they aren't as informative. Feel free to ask me question, I'm sure I can probably answer them unless they're obscure questions, then I'd have to look them up.