On the 17th of Last Seed, in the year 4E 201, the Dragonborn is captured by the Imperial forces whilst attempting to illegally cross the border into Skyrim from Cyrodiil. However, lorewise in the trailer for Skyrim and promotional arts, the Dragonborn is a male Nord warrior, wearing an iron helmet that bears a slight resemblance to the Nordic Helmet which Skyrim's culture is based on, a studded armor chest piece, iron gauntlets, and iron boots, carrying a steel sword and a banded iron shield.
The Dovahkiin can be from any race (human, elf, or beast) and either gender, depending on the player's choice during character creation at the start of the game before the prologue quest 'Unbound' in Helgen.