Desktops
Having a few desktops helps keep your workflow organized and uncluttered. Linux distros almost always have two or more desktops enabled by default, unlike Windows or MacOS which by default have only one. Apple introduced the convenience of more than one desktop years ago when it became a UNIX system, but it didn't catch on.
You have three enabled by default, but you can easily adjust the number by opening Menu --> Preferences --> Openbox, the Openbox preferences, clicking on the Desktop tab and adjusting the number you want.
Changing to Another Desktop
Look for the numbers "1 2 3" in your panel. On LXQt at the left of the panel at the bottom of the screen you'll see the numbers "1 2 3". On Openbox these numbers are in the panel at the left of the screen. Simply click on the number to change the desktop.
If you like using more than one desktop, keyboard shortcuts are a much faster way of switching from one to another. In Openbox, to change desktops press and hold down three keys simultaneously -- Ctrl-Alt-Right Arrow -- to change from desktop 1 to 2, or 2 to 3, and Ctrl-Alt-Left Arrow to change from desktop 3 to 2, or 2 to 1. Alternatively, Ctrl-Alt-1 will take you to desktop 1, Ctrl-Alt-2 will take you to desktop 2, and Ctrl-Alt-3 will take you to desktop 3.
In LXQt open Preferences -> LXQt --> Shortcut keys. Look for "Switch to Desktop 1" in the Description column. Then look and see what is listed in the Shortcut column corresponding to "Switch to Desktop 1". If, for example, "Control + F1" is listed, you can try "Control + F1,2,3..." to see if the combination works in switching desktops. It is good to have an application open in one desktop or another so you will notice the change -- if no apps are open all desktops look the same. If it works and you are happy with the combination, you can use it. Otherwise it is easy to change. You simply click to highlight the entry you want to change, for example "Control + F1" and then click the Modify button. In the window that opens, click the shortcut you wish to modify, in this example, "Control + F1". You will be given a 10 second countdown in which to type a new key combination, for example, "Alt+ 1" or "Alt + Tab + 1". Be sure to choose a combination that is not already in use. "Ctrl + S", for example, would be a bad choice as it's almost universally used as a shortcut for saving a document.
Also, if you find you would prefer a window to be on a different desktop, you can right click on the window's title bar and choose which desktop you want to move it to. At first this may all seem a little complicated but after awhile you'll be surprised at how quick and automated it all becomes and marvel at how clutter free and well organized your work environment becomes.
In this way, by arranging open windows over different desktops your desktop environment becomes clutter free and you can easily move from one application to the next without windows getting in the way of each other.