ima newb I dont even know how to put a background wallpaper on linux dslBackgrounds can be put anywhere you like, but the most convenient place, particularly when using the wallpaper tool, is /home/dsl/.fluxbox/backgrounds.
/home/dsl/.fluxbox is a hidden directory, so if you're using emelfm to copy files you'll need to press the "H" button next to the emelfm location window, or press Ctrl+h, to see the directory. Midnight Commander displays hidden files by default.
When you have your image(s) in place, go to "Desktop > Wallpapers" in the fluxbox menu.