Oblivion for the PC was my first elder scrolls game. I loved going through the guild quest lines and just exploring the world, but I always felt as if I jumped in the middle of the story. I understood sort of what was going on at the moment, but I didn't really understand the context of what I was doing. Is there an easy way to get familiar with the Elder Scrolls lore so that I can get ready for Skyrim?

read the books in the game.
 
or you can read them through the wiki.

There are tons of books spread throughout Oblivion. They explain much of the backstory. I would expect it will be much the same in Skyrim.

Play morrowind, if you can. It's dated, yes, but it's overflowing with interesting lore and tidbits about the world. Also, yeah, read wikis.

While I do, as a rule, promote the playing of Morrowind, I can see how that's not really an answer that you'd be looking for.

Wikis, as always, are the best place to start. Click something, click something else, etc. UESP (Marz's Link) is a very old and substantial wiki. ("Old" in a good way. It's not out-dated or anything.)

If you're looking for something a bit more pure, The Imperial Library is your source. In combines all in-game books with information given by the writers of the universe and such.

http://www.imperial-library.info/content/pocket-guide-empire-third-edition-seat-sundered-kings-cyrodiil

This is the more recent "Pocket Guide to the Empire." It contains and overview of every main race, as well as some basic information about the structure of the world.

I'm quite fond of the TES lore. It's one of the few Tolkien-descended fantasy universes that actually aspires to approach Tolkien's head-crushing complexity and metaphysical history. It doesn't really approach to it, of course, but at least it tries, and it incorporates some neat ideas along the way. The Cloven Dualalities principle remains pretty interesting.

Play Morrowind. 'nuff said

USEP wiki as others have said

Check this out if you're interested in the lore.

What is it about Morrowind that people love soo much? Far as enjoyment at the time of playing, Morrowind was my least favorite. The atmosphere is just drab...Sadly upon reflection, Oblivion is the only Elder Scrolls game Ive finished. Though I dont know I can be faulted for that. Between the riddles in Arena, and the unholy mess their first windows game was I dont know if it was actually possible!

I didn't have much problem just learning it as Oblivion went along, I'm sure the same will be true with Skyrim, so don't worry about it. The best teacher is immersion, and that's exactly what happens in a game like Elder Scrolls.

The Skyrim Blog has a feature they've been running where they give you the cliff notes on some of the backstory to the games. It's well-researched and concise, and an excellent starting point. Keep UESP open while you read it, and cross-reference anything you're interested in learning about further: (http://theskyrimblog.com/?p=1385)

@John1912 said:

What is it about Morrowind that people love soo much? Far as enjoyment at the time of playing, Morrowind was my least favorite. The atmosphere is just drab...Sadly upon reflection, Oblivion is the only Elder Scrolls game Ive finished. Though I dont know I can be faulted for that. Between the riddles in Arena, and the unholy mess their first windows game was I dont know if it was actually possible!

IMO Morrowind had the most interesting atmosphere of the bunch. Vvardenfell didn't really have that same same Tolkienesque vibe that most fantasy genre games borrow from, opting for a much more unique design from a landscape and architecture point of view. Also found the bestiary to be more interesting in TES3 (who doesn't love them some pack Guars).

http://forums.bethsoft.com/index.php?/topic/1112211-how-to-become-a-lore-buff/page__pid__16312374#entry16312374

@Marz said:

read the books in the game.

or you can read them through the wiki.

The wiki is all you really need. I wish more games would have such a great wiki.