Window managment is how to manage the windows on your desktop. Underneath Lubuntu uses openbox as default a window manager. This manages window allows you to drag and close and make windows take up the whole screen. You also can drag the whole window around by clicking on the titlebar and dragging the window with the mouse.
If you want to make your window bigger or smaller you can grab the border of the window which should be highligheted in blue by default to drag or make the window bigger or smaller. To make a window take up the full screen or maximize it is to press the button on the titlebar to make the window that look like to arrows pointing towards opposite corners of the window. Pressing the X button will close the window. The button that looks like a - will iconify the window to make it only appear on the taskbar of lxqt-panel and in the window switching dialog better known to microsoft windows users as minimize.
On the far left at the top of the window is the icon for the program. If you left click on the icon brings up a menu for window management. The send to desktop to send to desktop for several different desktops or all desktops at the bottom. The layer option on the menu always on top to make the window appear always on top. If you want to move something to always show to bottom or you can move it back to normal. The third icon is move and then you can drag them to where you want. Resize lets you move the mouse by resizeing. Iconify lets you see it only on the taskbar. Maximize maximizeses the window to make it take up all of the monitor. Roll up roll down makes the window just a titlebar. On the far bottom is this menu you can move it to close.
If you want some useful keyboard shortcuts use the super (windows) key and press an arrow key to snap the window to that side of the screen.
