If you are expected to bring a character you should definitely bring that. If you're going to make a character there you should come with an idea about the following things (but remain flexible, you idea may not be exactly what you end up with).
- Character name
- Character race (Human, Dwarf, Elf, Halfling)
- Character archetype (loyal knight, scheming wizard, back-stabbing rogue, etc)
As far as rules knowledge, the Players Handbook (PHB) helps but it will speed things along greatly if you know these few simple rules.
- For most things you will attempt (including attacks) you roll a d20 (that is a twenty sided die), add a modifier, and compare it to a target number. If your total equals or exceeds the target you succeed (hit, pick the lock, whatever).
- You have abilities. Some you can use all the time, these are called
At Will. Some you can use only at intervals. These will be Encounter or Daily.
- You have hit points and healing surges. These represent how alive/tough you are. If you run out of hit points you start dying. You can use healing surges to regain your hit points in certain situations. A healing surge usually regains one quarter (1/4) of your total hitpoints, rounded down.
- We refer to dice by the number of sides they have, preceded with a d. A d4 means a four sided die. 3d6 means three six sided dice.
- When in doubt round down.
- The DM overrules the rules.
Most of all, remember you're there to have fun! The other players and DM should be willing and able to help you with the details
Generally speaking, when you go to role-playing game, you should have at least some blank paper and a pencil.
In your case, as this is a beginner event, they will very likely be providing the books and dice, and pre-printed character sheets, if any. However, do not expect them to provide a writing instrument for you, and this is quite vital.
In any game other than Star Wars (Fantasy Flight Games), you might be expected or encouraged to bring your own basic set of polyhedral dice. Anecdotally, demonstrations at one of my Friendly Local Game Stores would not provide dice, and would advise new players to go to the main room and purchase a Chessex set.
However, this being a Star Wars event, you can expect them to provide the dice, as the game uses special dice that no one has. (Also, at time of writing, the dice are expensive, backordered from the manufacturer, and generally hard to come by, so if they expect to teach players the game, they would have to provide them.)
You should not be expected to have the book for an introduction or demo. Keep in mind, the store is running this event partly to encourage you to buy the product, so already having the product would be counter productive.
If the demonstrator/instructor is kind, they may provide blank paper for notes and writing instruments, but do not count on it. You should always have something to write with and write on.
If you want snacks or drinks, you should bring your own (unless the game store sells some, in which case, purchase your snacks from your game store). Do not expect the demonstrator to provide them, or the other players to share. That said, bring extra and share if you can manage it.
Best Answer
It is generally helpful for players to have a Player's Handbook readily available, especially for spellcasters who need to reference spell descriptions every now and then. Aside from that, the most help that it will do is speed up character generation and leveling-up, which is good at the table because it allows for more game-time in the session. I find that in a party of 4 players and 1 DM, having two Player's Handbooks available is generally acceptable for our group, though more would be spectacular. In your case, your table should have 3-4, possibly one of which would be for the DM to reference behind the screen.
Hope that helped give you some additional perspective on the matter!