There is likely no /etc/samba/smb.conf file, so you are creating a new file.
Normally there is an /etc/samba/smb.conf-sample file that is heavily annotated and can be quite confusing. The idea is that you can edit this and save it as /etc/samba/smb.conf.
I recommend Samba by Example
as the most useful reference I have found. There is also a PDF