Well... first off, i would suggest using Invision Power Board
, its free also, and a much better/quality board. There are tons of hacks/mods/skins as well.
Anyways back to your question
That.. i can't really answer you on that. Did you install PhP on the server as well as MySQL? Perhaps some of the files/directories you created doesn't have the correct chmod as this is very important?
As far as creating your database using a newly installed message board, it practically does all the work for ya, you just supply the needed information. If there is an error, it let you know, some you can bypass the error or you can figure it out and try the install again. Sounds to me that you went ahead and installed the message board till complete and then now you having problems with the database? Ahh hell.. i'm confusing myself here.
Your best bet is go to their support forum, i'm sure you'll get a quick answer.