Hi PC Genie. Here is what you need to do…
Step 1 – Download FreeNAS to your PC http://freenas.org/download-freenas-release/
Step 2 – Download UNetbootin to your PC https://unetbootin.github.io/
Step 3 – Run UNetbootin. Select the “Diskimage” option. Follow the instructions you see on the UNetbootin page.
**** From there, just plug in your USB drive into a PC that is turned off. Then power it up. The PC must be set to boot from a USB drive, or else it will always fail ****
Please Note: Sometimes UNetbootin does not work with some operating systems like FreeNAS. If it does not work with the FreeNAS version you are using then switch to a different program that is similar to UNetbootin. Here are 2 different programs that do the same thing.