Learn GIMP - you won't regret it. I'm a GIMP expert, and I've got 10 tips for getting productive faster with this great Photoshop alternative.
It’s fairly easy to blend two images in GIMP. All you have to do is: Open the two Images in GIMP. Blend the images using layer opacity/blend mode/layer mask. Export the resultant image as JPEG/PNG.
One of the most popular image editing tools is GIMP, and there are good reasons why this is the case. Yes, it is not as easy to use when compared to Photoshop, but we cannot complain about that ...