How Can I Open Pages in Full Screen

[Ray&Paula]

I have a new 2016 MacBook Pro and would like to know how can I open Pages in full screen? I can only expand it by using the upper left corner green arrows. I also have Prefer tabs when opening documents "In Full Screen Only" checked in the dock preferences window within system preferences. When I click on Pages in the dock a window comes up in the middle of the screen. Not sure what this window is called but, it has a side bar showing Favorites such as Recents, All My Files, iCloud Drive, Applications......... and so on. If I click on the bottom left tab called "New Documents," Pages will come up but, not in full screen. I then have to click on the upper left green arrows to bring it to full screen. I was under the impression that all apps would open in full screen if you exit in full screen. If someone could walk me through the process for correction, I would sincerely appreciate it? Thanks, Ray