Heya Sartredes. If you want to catch up on the lore, the best way is reading old source books. Most of the older stuff (3rd edition and back) can only be found in PDF form, or on eBay/Amazon, but 4th edition books should still be floating around in hard copy. I'd suggest finding the Sixth World Almanac. It is basically half history and half world overview. Good for getting you a basic feel of the Sixth World as a whole, as well as some of the history. Also, the Seattle 2072 book is great for info on Seattle, the 'main' setting for the game.
Other than that, feel free to ask questions (the Secret History section is especially good for lore-delving), and feel free to chat with CanRay about all his experience playing the game.