PiNet comes with the amazing stars background photograph taken by John Lemieux.
If you want to change it to your own custom background image, the image is stored in 2 places.
/opt/ltsp/armhf/usr/share/images/desktop-base/PiNet.png
./opt/ltsp/armhf/usr/share/ldm/themes/raspi/bg.png
.If you wish to change either of these images, all you have to do is overwrite them with your new image.
For example, to replace the desktop background
sudo cp /home/myname/myamazingimage.png /opt/ltsp/armhf/usr/share/images/desktop-base/PiNet.png
Note the images must be in PNG format.
##Changing the login screen logo
The default login logo is the Raspberry Pi logo, if you wish to change it, apply the same process as above.
It is stored at /opt/ltsp/armhf/usr/share/ldm/themes/raspi/logo.png
.
Make sure your logo is also in PNG format and has transparency enabled!