Here is the quickest way to share a folder with read/write access.

Get rid of all lines in your /etc/samba/smb.conf and replace them with:

[global]
workgroup = workgroup or domain
server string = %h server
security = user
obey pam restrictions = Yes
passdb backend = tdbsam
passwd program = /usr/bin/passwd %u
passwd chat = *Enter\snew\sUNIX\spassword:* %n\n *Retype\snew\sUNIX\spassword:* %n\n *password\supdated\ssuccessfully* .
syslog = 0
log file = /var/log/samba/log.%m
max log size = 1000
dns proxy = No
panic action = /usr/share/samba/panic-action %d
encrypt passwords = yes
invalid users = root

[Share name]
path = /home/share/
comment = comment
public = yes
browseable = yes
writeable = yes
valid users = user who will access the share
create mask = 0755

Restart your samba server:
/etc/init.d/samba restart

You must have an smb account for specified user. To create one:
smbuser <username>
smbpasswd <username>

Enter password for user.