Open the smb.conf file for editing (gksu gedit /etc/samba/smb.conf) and look through the Share Definitions section, it seems to have all you need.

#======================= Share Definitions =======================



# Un-comment the following (and tweak the other settings below to suit)

# to enable the default home directory shares. This will share each 

# user's home director as serverusername

[homes]

   comment = Home Directories

   browseable = yes



# By default, the home directories are exported read-only. Change the

# next parameter to 'no' if you want to be able to write to them.

   read only = no



# File creation mask is set to 0700 for security reasons. If you want to

# create files with group=rw permissions, set next parameter to 0775.

;   create mask = 0700



# Directory creation mask is set to 0700 for security reasons. If you want to

# create dirs. with group=rw permissions, set next parameter to 0775.

;   directory mask = 0700



# By default, serverusername shares can be connected to by anyone

# with access to the samba server. Un-comment the following parameter

# to make sure that only "username" can connect to serverusername

# The following parameter makes sure that only "username" can connect

#

# This might need tweaking when using external authentication schemes

;   valid users = %S

Un-commpent means removing the ; from the beginning of a line (don't remove the hash signs). Uncommenting stuff in the first two paragragraphs, and setting the home directory to be writable and browsable, the way I've done above should really be it.

Save and exit when done, then restart samba with sudo service smbd restart.