Well, i will sum up the end of Warcraft 3:Frozen Throne expansion for you. A Night Elf dude that was exiled thousands of years ago(named Illidan, night elves can only die if killed), and he really thought he was right, he was a enemy but i truly thought of him as something like Riddick, a bad guy doing good things one way or another. Anyways, he teamed up with Blood elves( a decendent of the High elves who are decendents of Night elves only the High elves are greedy with magic), and the Naga(forgot about their originality but their those cool looking scaley fish people, not the murlocs by the way) and they all went to Outland, the home world of the Orcs(Orcs made the dark portals all the way form the earlier games which ripped their world apart) to do something or another. So somehow we are in Northrend, a continent on in World Of Warcraft but its an icy place(you guessed it) up north. That is where Illidan tries to stop the corrupted Prince Arthas from reaching the throne. He fails and to this day Arthas is trapped in his icey kingdom(the throne is where the Lich King, lord of the Scourge, was, Arthas and the liches spirit bonded). So Illidan and his companions went back to Outland.
Now, 6 years has past since the Frozen Throne, and the undead on the horde side is ruled by a woman named Sylvanas, she leads the Forsaken undead(broke off from the scourge, now have free will and you COULD say arent exactly evil, some of them anyways). Now that the war is over, and the orcs are not bound to a blood pact with a dead demon, the orcs also do not have to be so blood thirsty. The only human kingdom now is that of(forgot what the name of it is) Stormwind.
So, now the drums of war are coming once again, and the tension between the Horde and the Alliance has reached its limits.
now of Burning Crusade(expansion coming out in June):
Not long ago a ship(call it what you want, its a space ship but that sounds to modrernish) called Exodas crash landed holding a large group of the remaining non-tainted Draenei are. They were seeking Azeroth because they heard of the rumors of this world defeating the Burning Legion(warcraft 3 non-expansion), which is a vile demon group that has destroyed who knows how many planets. Plus, now that the Dark Portal(gateway from Azeroth to Outland), is open and the Bloodelves(now on horde side) are in their old land of Quel Thalas. Level 60-70 mobs are in Outland plus many stunning instances/dungeons. Thats what i know so far.
SORRY if im confusing especially with me ( and ) everywhere. Ever since Kindergarden i played Warcraft 2: Tides of Darkness, so the history i know in me enough its hard to explain each it, i just scratched the surface.
NOW FOR SOME ADVICE!!!
Are you on a RP or RPPVP(roll playing or roll playing player vs player) server? If not you might want to since you like story line. Recently the dwarves have been wanting to know of their past(they are one of the oldest races on Azeroth). Plus their drinkers, so its fun be be them.
My suggestion for feeling in the mood of a story is reading this and that first link.
Heres another link i found quite awhile back:
http://www.blizzplanet.com/modules.php?action=Content&pa=showpage&pid=175
Much less heavy of a read.
Alright well i hope i helped in SOME way!