Summary of Halo story?

Ok so here's the situation: I never played the Halo series before, so with Halo 4 coming and everything, i decided to start from the beginning. I grabbed a copy of Halo CE and started playing. But it was like i was thrown in the middle of something.

By the end of the game i still didn't understand what was going on. Then i picked Halo 2 just to be more confused. I know that there are countless Halo books out there, but i have many books to read and i can't read them.

There is still the problem of chronological order, i don't know what order i should play the games and read the books.

If anyone could tell me (or find something on the internet) that could summarize Halo plot for me, i would be very, very grateful.