Here's a quick tutorial of how to setup your computer for multiple monitors.
Right click anywhere on the desktop and select "Display Settings". This will bring up this screen:
On this screen you can change the orientation of your screens by dragging them around to the correct positions.
You also can change whether screens are a duplication or extension of each other, the amount of zoom each screen has, and which one is your primary screen as you scroll down:
Whichever screen you use on your smart board should be your main display if you want to use the onscreen keyboard.
If you've turned on your computer but can't find your logon screen that can be due to the Smart board being the primary screen and showing the logon even though it isn't powered on. You can either power on the projector/smart TV, or just slightly unplug the display cable going to it on the back of your computer:
Plug this back in when you want to use the projector/smart TV.