This RP is set in the days of the old republic, some 3650 years before the star wars movies. You do not need to read up on very much to begin with. Reading the article linked above about the sacking of Coruscant will give a rough idea. 

The key difference from the later eras is this:
The Jedi order actually has guts. They don't hesitate to kill Sith. Their policy of "the only good Sith is a dead Sith" is pretty apparent.
Marriage or other such relations between Jedi, while not strictly forbidden, is frowned upon.
Many republic citizens do not really appreciate the Jedi these days.
The Sith number in the thousands (probably in the tens of thousands). 
The current timing is just at the start of the cold war between the Sith empire and the Republic. The Sith just forced the Republic to sign a treaty that put the republic at a serious disadvantage. Holding the republic capital hostage will make dictating terms pretty easy. 
Lots of people on both sides aren't pleased with the treaty. The republic side for the terms, the Sith for ending the war.
Reading up on a bit about the situation in those days can help. 

You can always read up on the IC thread, but considering just how massive it is, that'll take a while. While most of the posts there are pretty large, they are also mostly collaborative works written by two-three people over considerable time. The requirements for post length will remain the same as for advanced in general. (decent lingual quality, 3-5 paragraphs).

For Jedi characters, they can also be part of an upcoming strike against the prison ship Hâsk. The Darth in charge of this operation announced out to the empire just what she had acquired recently, so even the stupidest SIS Agents (strategic information service, I.E. the republic's spies) would've been able to get hold of that message and relay it back.

For Sith, the invitation (up top in this thread) is relevant. They would come aboard the ship when it arrives in orbit above Teth.