To change the desktop background you can either type the path of the file you can type in Wallpaper image file or use browse to bring up a dialog to choose which the desktop.
The drop down menu for icon size lets you choose a different size of desktop icons you can chooose a size that looks good on your screen.
The box labeled select font lets you choose which font and size information from a dialog box. On the left is a box for which font to select on on the bottom or type the name on top. The middle lets you choose the font style of the font on your desktop. On the far right is a choice for the size of your font which you can select from the menu. The box for text color brings up a widget to pick color of either the text color or the shadow color of the icons.
To launch desktop from the menu -> prefrences -> LXQt settings -> Desktop. Or from LXQt configuration center press the desktop button to launch it or run pcmanfm-qt --desktop-pref. Another way to launch this is to right click on the desktop desktop prefrences.
