This is the first on the general software tips series, just a quick tip on how to join two images together in GIMP.
File > New; create a new image with an image size that is bigger
than the combined size of the two images that you are combining
File -> Open as Layers ; open the images you want combined
Use the Move [M] tool to arrange your images as you see fit
Use the Crop [Shift+C] tool to crop the images after rearranging them
File -> Export : save your combined image to the desired image format