Getting Started :
The first thing you'll need is to create a character, which you can do following the instructions found here : Character Creation. You'll then need to find people to play with. A group needs a Game Master to play all the non player character (NPC's) such as the bartender you might talk to, the suave bard who crosses your way, or the cranky cleric who you bump into. The Game master will also need a good understanding of the rules to run the World in which your characters exist. A group of players can be of any size, but it is important to remember that everyone is there to have fun, and sometimes there are too many cooks in the kitchen.
If you are a player in the game, you'll need a grasp of the Basic aspects of the system. A more detailed version can be found at The Basics, but here is a brief rundown of how the system is played.
Most actions are resolved by using two ten sided die and adding modifiers to it. For example :
Matt is playing a level 1 Fighter who wants to try climbing a wall. The GM tells him that it is a simple rock wall with plenty of hand holds and rough outcroppings and it is a Trained level Skill check, which is DC 15. Matt looks at his character sheet and sees that he is a skilled climber (+2) and has a good strength modifier (+3) giving him a total of +5. He rolls 2d10 and gets an 11. He adds the +5 modifier to that and has a total of 16, meaning it's a success.