Hi so I got a external hard drive 3tb so I plugged it in and I download the app and is that it or do I need too do anything else also it blinking blue lights
You need to format it on the Xbox One to accept either games and apps or video and music.
Then you're done.
Plug it into the USB Port in the back of your console and plug it in to the mains socket.
When you turn on the XBox ONE you should get a notification that you have an External Storage Device and an invitation to "Format" it.
Formatting it will make it work with your 360 games.
Once you've done that then you can move stuff to the External Storage Drive by going into "Storage" in "Settings".
You can also set it up so that new games will be installed there automatically.
Hope that's helpful.
K thanks guys