Check out the sticky threads at the General Modding part of this forum: there you should be pointed out to a few tutorials on how to get started
Be wary, though, that many aspects of the game are hard coded and can't be changed. I'm pretty sure that race is one of them, as in you can't add a new one or make substantial changes to them.
There once was a sub-race mod I had on my original copy of BG2 where once you made a character an invisible NPC would appear and initiate dialogue with you. From there you could pick a sub-race and it would apply the stats to you from there.
Comments
Be wary, though, that many aspects of the game are hard coded and can't be changed. I'm pretty sure that race is one of them, as in you can't add a new one or make substantial changes to them.
Good luck!