I always thinks its a good idea to read at least the start of http://us3.samba.org/samba/docs/man/Samba-Guide/
or the official howto on the samba site. it will, if nothing else, get you to the point where you can ask some specific questions (or in the case of post #3, I suspect give you a direct example).
EK, do you have something like
create mode = 777
directory mode =755
in your share definition?