You have a pretty picture, but the background doesn't suit you. Did they really desperately need to be photographed against such a background? Don't worry anymore about photography, however, this article will show you how to get rid of the background using the GIMP Outline Selection Tool.
Step 1. Open the image
Step 2. Cut off excess parts of the image
Click on the rectangular toolbar and select the part you want to keep. Then click on Image> Crop to crop the image.
Step 3. Click on the Path Selection Tool
Step 4. Zoom in on the image, zoom in to the place where you want to start
Step 5. Start highlighting
Remember: when selecting a path, the less you make, the better. Click and add a point only where the line changes direction. Continue until you have completely drawn around the area you want.