Well, there may be more than one possibility.
1. Do you want your samba share to be public or accessible with authentication? In the [global] section, if you want the share to be accessible with authentication (not public), you should put "security = user", not "security = share".
2. What password backend do you use in samba? If you don't define it in the [global] section, I think the default is "tdbsam". Is it tdbsam where you added your samba users?
3. Do you have the root user added in your samba password backend (i.e., tdbsam)?
4. Do you have the user "zirto" both in the unix user database and in the samba user database? Passwords don't have to be the same.
5. What permissions does the user "zirto" have for the "/home/share" directory from the unix side? They should be rwx.
I would suggest to leave out all the fineties and test if it works as a simple, public file share first. Then you can add authentication, printers, printer drivers, whatever.
For the simplest file share:
1. Add the root user to your samba password database:
smbpasswd -a root
<enter a password>
2. Make the share's permissions read/write/execute:
chmod -R 777 /home/share
3. Put a very simple smb.conf file:
workgroup = workgrp
netbios name = smbserver
server string = public server
security = share
browseable = yes
hosts allow = 192.168.1. <of course, adjust it to your LAN>
path = /home/share
comment = testfiles
read only = No
guest ok = Yes
4. Test if configuration file is "sane":
5. Restart samba.
6. Test from the server, if samba lists its share:
smbclient -L smbserver
7. If that works, try to access it from the windows machine.