Removing Background colours by bi_bi_love

Cutting out the background, if it's a solid colour use the "Select by color" tool

Once you have selected all the background you want, press ctrl+i (this inverts your selection, ie the foreground).
ctrl+c (copy)
open a new transparent layer
ctrl+v (paste)
you can hide the background layer and fine tune your foreground layer.
save as .xcf file to preserve the layers.