Wow. Great response, thanks guys.
I think if we do it here it might help another noob in the future.
I'm getting to grips with some of the Gimp functions - my copy has a gif converter, so that should take care of colour conversions, and this image has only very basic colours anyway.
Image->Mode->RGB. That's what I needed to start with, thanks. (I think. I'll check it out later). Once I can access the colour tools, I'll probably muddle through, though to save me some time and experimentation, my next question will be:
Is it possible to change a range of colours (eg several shades of blue into several shades of red) simultaneously, or will I need to pick out and convert each shade individually? I did manage to adjust the colour selector slider to pick out all the blues in one go, but since I couldn't access the colour changing tools I couldn't experiment with changing them to a similar range of reds.
Here's a link to the little gif I'm playing with.
Maybe it's one of yours? Just look on this as sincerest flattery.
Gimp gives me access to the individual frames of the sequence, and I want to play with changing the colours to get a feel for how the flag is painted. Eventually, when I've figured out exactly how it's done, I want to use this image as a model to create my own copright-free flag-waving smiley and produce it with a range of different flags.
The smiley is simple, even I can draw one of those from scratch, but that fluttering flag is not so easy. I'm thinking that if I want to produce a range of these, the best thing would be to create the fluttering and shadowplay separately (is that what's called a mask?) and see if I can use flat colours for the different flag designs. I think that's going a step beyond the original and might be beyond my skills, but if you don't try...
I couldn't do gifs at all until last week.