I really like the example icons with transparent backgrounds supplied with the examples on my Tufty2350. Could I ask how they are produced in GIMP or some other free photo/image editor?
I’ve managed to get a transparent background of the correct size but I’ve not been able to add an opaque layer above it and put some coloured pixels on the new layer.
You can hit CTRL-L to go to the layer window. There, you can add, delete and move layers. You can add transparency to indiviual layers (I think it is on by default) and you can set the level of transparency and how the layers are merged.
Once finished, you should merge the layers to a single layer. Make sure the bottom layer also has transparency set (i.e. has an alpha layer).