[PROBLEM] SMB user config

[Eisregen04]

hey hey,
i set up my pi with xbian and first to say it works great ( media play, library )
i am new to linux, i know how i can connect to the pi with putty
Now i try to set up smb so when i connect from my pc (WiN 8) to the pi he will ask me for a user and pw, in config i found write access but only for everyone eg anonymous and i dont want this

i got it that he ask for a user and pw for the default folders "xbian" "xbian-xbmc" "system-logs" but not for my connected usb hard drive, how can i set this up ? And is it necessary to create multiple users for every pc in the network or can all connect with the same user/pw?
probably its necessary for more user accounts for only read and read/write access.

Sorry for my bad english it is not my main language but i hope anybody can help me.

Software
XBian version: latest ( installed 2 days ago) 1.0 beta 2 i guess
XBMC version: included in the xbian installer
Overclock settings: none

Hardware
Power supply rating: 1,2A 5V
RPi model (model A/B 256mb/512mb): B / 512 mb
SD card size and make/type: SanDisk Ultra 16gb 30mb/s
Network (wireless or LAN): Lan
Connected devices (TV, USB, network storage, etc.): TV , USB Keyboard and 1TB HDD