GIMP/Photoshop
Step 1:
Resize the image, via the ‘image size’ option under the image tab.
Change the image to desired size, in this case to a height of 500px.
Step 2:
Remove the background of the image with the magic wand tool.
Adjust the tolerance levels till appropriate.
Step 3:
Insert the desired background image into the project.
Ensure that the background image is below the original image.
Step 4:
Profit.