Using two or more programs together can make a system more powerful. In this case we want to use Tuxpaint and the Gimp. We will start off using Tuxpaint to make a picture and then take a screen shot just of the drawing.
The let's import a picture we have downloaded and use Tuxpaint to edit it and then of course to take a screen shot of that.
Then we need a screen shot that was made a while back.
The we need to open up the Gimp and set up a new page several times larger than the pictures and then import the three pictures.
Then you can export that picture and import it into tuxpaint for final editing.
So then you can use it in a web page like you blog or where ever