setting permissions for another user

[Vincent Caintic]

i'd like to give another account on my computer access to write folders on my
mounted win98 partition. that account only has read access to them by default.
however, even when i attempt to change the permissions using chmod under root,
the folder always has the permissions 0755.

i'm still new to linux and haven't really messed with permissions before, so
this might seem dumb and the above might be irrevelant info. anyway, how do i
change this?

thanks for any advice.