The races from the Player's Handbook are all available. If you want to find a likely starting location for your character:
Humans: anywhere
Halflings: Idee, Hollow Hills, Urnst, Ulek
Eladrin: Celene, Spindrift Isles, Ulek, Sunndi, High Folk
Elves: Granwood Forest, Ulek, Vesve Forest, Celadon Forest, Nyrond
Dwarves: Iron Hills, Irongate, Onnwal, Ulek, Ratik, Sterich, Glorioles
Tiefling: anywhere, but mostly in the Great Kingdom and the countries bordering the Crystalmist Mountains and Hellfurnaces in the West. There is rumored to be a Forgotten city of Tieflings in the Sea of Dust. Some Tieflngs speaking a strange dialect have begun to appear in the easternmost countries recently as well.
Dragonborn: anywhere, but there is a rumored secret city in the Vast Swamp
Half-elves: anywhere, but most common where there are populations of Elves or Eladrin (as above)
The list is far from exhaustive, but should give you a choice of starting locations for character background