xcode run&buid good but

Hello! to all of you PPL
this is my first post, and yes is to ask for some help
I'm running leopard 10.5.6
i have the iphone SDK installed (XCODE) in the default directory
when I make a little app for the iphone runs perfect it execute the simulator good
the thing is that when i write the "hello world" app for osx in xcode
at the button say succeeded but it wont show nothing no terminal window nothing (weird)
it is supposed to show a terminal window with the output text "Hello World" but not
that's my problem not sure if i have to make an environment variable (don't know how...)
any help
well I'm just started to learn objective-c
THNKS