First: Read at least these key posts:
Rules of Conduct
What is this place?
What is a seed post?
Realms Climates
Realms Maps (printable)
Signatures & Graphics
Realms: Sex & Language
Using Realms' NPCs
Points Of Interest (POI) - May be skipped. Within each realm's folder a copy of all relevant information having to do with that realm is provided. If you don't want to read up on all the realms, just go to the folder with that realm's name.
Next.
Before you get into the realms you should decide where to start.
If you want your character to be a new arrival to the realms, you should begin by having them come from the black lake, something like what is described on the start page of this forum. It should be noted that new arrivals are usually picked up from Weeping Winds Isle by ship. As Zia's Inn and Camira City are the closest, a new arrival's rescuers will usually come from either Zia's Inn or Camira City.
If you want them to be someone who was born in the realms, then you'll need to figure out where you want them from within the realms.
If they're not a new arrival or someone who was born in the realms, then you should give some idea of what they've been doing since they arrived, or maybe where they may have been spending most of their time while in the realms.
This bit of information is part of your character's history and gives everyone some idea of what and who they're dealing with in play.
Any of these ideas can easily be included in your character's bio. When someone reads your character's bio they will be able to see how that character connects to the realms.