1. download the IMG (for i386) from http://freenas.org/
2. write into USB手指
3. in BIOS boot from USB手指
4. Plug-in LAN
5. Config DMZ+FreeNAS
for 1.
you can download FreeNAS LiveCD and boot from that LiveCD (use ext-ROM / whatever)
then you can transfer the IMG from CD to USB手指 / int. SSD
and then next boot can boot from USB手指 / int. SSD, no need that LiveCD