Here's how you can combine them.
Preparing the Canvas
1. Open GIMP.
2. From the File Menu choose Open to open the two image files. You'll find that they open on two different canvases.
3. You'll need a third canvas to work on; customized to accommodate both images. You can open a new one from any of the already open canvases. But how do you determine the size of your new canvas?
4. To do this, click new from the file menu of the chili canvas. It opens a dialogue box to help you create a custom canvas. It also has the image size information of the canvas you opened it from.
In the image below, you can see that the size of the chili image is 77 x 285px (pixels or picture elements).
5. Do the same with canvas 2 and note the image size. It is 368 x 224 px. So, to work comfortably, the third canvas should be 368 x 285 px. Let's round it up to 800 x 300. I have doubled the width. You'll understand why when you start working on a similar project. Enter 800 against width and 300 against height as shown below and click ok. You now have a new drawing board that's just the right size for combining the images.