If you're trying to use two apps on a Windows PC on the same monitor, you can quickly organize them with one of the following methods:

Click and drag the top of the window to either edge of the screen. The app will move to that half, and Windows will prompt you to put a different app on the other side. See the video below for a demonstration:

Alternatively, you can hold the Windows key and use the arrow keys to quickly move the current app around, maximize, and minimize it. Feel free to experiment with it until you get the hang of it.