How do I make the top tab bar stay on the screen all the time

"Top tab bar"?

The top of the screen is where the applications menus appear on the left and system icons (time, volume. etc) appear on the right side.

This entire area is "covered over" when you enter into "Full Screen" mode. You can expose it while still in full screen by moving your cursor over the area.

If you want the Menu Bar to always show, take your open apps out of Full Screen Mode.