race's?
The differences between races are mainly:
1) Looks
2) Story (at least the first 30 levels of it)
3) A few racial skills (but these are generally weaker than profession skills)
Thus it isn’t the case that Norn warriors are stronger than Asura warriors or anything like that, nor do they have different strengths and weaknesses.
See here for more info: http://wiki.guildwars2.com/wiki/Playable_races
What race you pick has no bearing on your characters stats, so it is as Diovid points out mainly a cosmetic choice – with the exception of the storyline and a couple of racial skills which do differ across races.
Select: Make a Character and look at their descriptions.