Ghost -- if I'm reading you right:
BSD is not software, it's an operating system. You put it on your usb stick, reboot your computer from the usb stick, and the operating system (BSD) will start.
I agree with Hagiri to use dd to install the GhostBSD img file onto your usb stick. If you want to make a permanent installation that saves all your changes, i think you'll need to download the GhostBSD iso file and burn it to a blank CD (that's NOT like burning a music CD or backing up files to a CD). Then you start your computer from the CD; when the menu comes up, choose "install" to install GhostBSD to your usb stick. After that's done you can start your computer from the usb stick anytime -- you will have a complete operating system on your stick, usable on most any computer.
All this said, I'm not trying to insult your intelligence if you already realize all this; if so, please try rewording your question and reposting. On the other hand, if you've never worked with images and downloading/installing BSD or Linux, let us know, maybe we can point you to a couple places that can get you started.