These are things I did Inside [Seat:*] in
greeter-session=lightdm-gtk-greeter autologin-user=pi autologin-user-timout=0
I changed the background to my preferred one by
[greeter] background=/usr/share/pixmaps/splash.png user-background=/usr/share/pixmaps/splash.png
I will see the background wallpaper when autologin is not enabled, but I have to log in manually. When auto login enabled I am logged into the black screen with the mouse and no wallpaper.I want the wallpaper to appear in autologin too.I already spend a lot of time on this.I have tried Openbox without lightdm also using feh.But autologin and startx had to be done manually.As I am not well versed with xinit.I am trying to do it for the kiosk to show a wallpaper before loading time taken by chrome to fetch website.