hi sonia - welcome to the group!
first of all, i hope you had a great time at the concert that you went
to :) it's wonderful that bryan decided to tour south america once
more.
BA likes his privacy, so as far as i know there is not a place where
you can write to him personally. you can try sending your letter to
the e-mail addresses found on ba.com and hope that they are forwarded
on to him. he also has a myspace page, so you can try there as well.
and then again, there is always the old fashioned snail way to the
fanclub :)
cheers!
tricia :)