I'm not sure if this already is relevant for a newbie following introductory howtos, but you should note that the command line environment in your regular desktop Linux is different from what's on this (and many other embedded) device.

I recall 770 uses busybox, which I think replaces some of the regular Linux utility binaries, was that correct? You can probably find help for busybox with google. Also the shell is not bash but ash, which likewise is a more stripped down alternative. If you are interested in learning how bash works, you could install that on 770