please help me!

[amarchi]

first at all: sorry for my bad english )
i need to install owa in DMZ.
I don't know much about the pix 515, i have tried to configure some static and some access-list, but i need some explanation about the global and nat commands
this is a partial configuration of my pix515
can you help me?

PIX Version 6.2(1)
nameif ethernet0 outside security0
nameif ethernet1 inside security100
nameif ethernet2 dmz security10
fixup protocol ftp 21
fixup protocol http 80
fixup protocol h323 h225 1720
fixup protocol h323 ras 1718-1719
fixup protocol ils 389
fixup protocol rsh 514
fixup protocol rtsp 554
fixup protocol smtp 25
fixup protocol sqlnet 1521
fixup protocol sip 5060
fixup protocol skinny 2000
names
name 10.10.1.5 mail
name 11.11.11.11 dns_server
name 11.11.11.12 webmail
access-list outside_access_in permit tcp any host 13.13.13.13 eq smtp
access-list outside_access_in permit tcp any host 13.13.13.13 eq pop3
access-list outside_access_in permit udp any host 13.13.13.14 eq domain
access-list outside_access_in permit tcp any host 13.13.13.15 eq www
access-list outside_access_in deny ip any any
access-list 101 permit ip 10.10.0.0 255.255.0.0 10.10.0.0 255.255.0.0
access-list dmz_access_in permit tcp any host mail eq 135
access-list dmz_access_in permit tcp any host mail eq 5001
access-list dmz_access_in permit tcp any host mail eq 5002
ip address outside 13.13.13.13 255.255.255.224
ip address inside 10.10.1.1 255.255.0.0
ip address dmz 11.11.11.1 255.255.255.0
global (outside) 1 interface
global (dmz) 2 interface
global (dmz) 1 11.11.11.6
nat (inside) 0 access-list 101
nat (inside) 1 10.10.1.6 255.255.255.255 0 0
nat (inside) 2 0.0.0.0 0.0.0.0 0 0
alias (inside) 13.13.13.14 dns_server 255.255.255.255
static (inside,outside) 13.13.13.13 mail netmask 255.255.255.255 0 50
static (dmz,outside) 13.13.13.14 dns_server netmask 255.255.255.255 0 50
static (dmz,outside) 13.13.13.15 webmail netmask 255.255.255.255 0 50
static (inside,dmz) webmail mail netmask 255.255.255.255 0 50
access-group outside_access_in in interface outside
access-group dmz_access_in in interface dmz