My Scratch disk HD failed and trying to install new unformatted HD

I have a 2010 (5.1) Mac Pro and the Macintosh HD failed and I have a new Toshiba x300 HD that is unformatted that I would like to install internally. When I have the new HD in slot 1 and no other HD’sd installed I turn the computer on and only get the grey screen. If I turn on the Mac Pro with the new HD installed while holding Command R I get the folder with question mark error message. How should I proceed? Once I format the HD I have the High Sierra OS on a Lacie external drive that I am hoping I can use to load the OS onto the new HD on my Mac Pro.