If it's not already visible, enable the mouse cursor (default: F10)
Right click on the screen and select "new info window" from the pop-up menu.
Alt-click on the window to select it, then right click on it and select "customize" from the pop-up menu. The reason alt-click is needed is to differentiate between clicking on windows and clicking on cockpit instruments/levers/etc.
In the customization, on one column you will see the available displays and on the other one (which will probably be blank since it's a new window) you will see the displays enabled for that window.
Find the "motor controls" display in the list of available ones and click on the arrow-labeled buttons to move it to the list of enabled ones.
If needed, resize and drag the window where you want it on your screen.
Optional: you can further customize it by hiding the borders and title bar. Doing so will remove the ability to rezise and move it respectively.
Left-click outside the window to deselect it.
That's it