YOUTUBE TUTORIAL
I have created a tutorial of source creation and posted it on my YouTube Channel. I did create this source in Photoshop, but I want to emphasize that nothing I did was overly difficult. Everything I did in this tutorial can be used in Pixelmator, Krita, Affinity, or any other application that supports layers and blending modes. It is a very basic tutorial utilizing no fancy tools.
Here is the finished source
1 . Here is the layer I started with. This is a landscape that I created in Midjourney. I never use Midjourney for my final sources, but I will often use components that I will put into source creation.
2. These are more trees that I found somewhere. I use this image a lot. I don't remember where I found it. I just have it in a folder of source material. Keeping folders of generic source materials that you love is super useful to speed up the process of source creation. I have a folder of flowers with the background already removed, just sitting on my desktop, because I use flowers so much in my sources.
I talk about that tree right down the center in the video. Placing a focal point in the center of a source/painting is BAD composition. I missed it when I was creating the source, but I did fix it when I created the painting.
3. This ruin was another Midjourney creation. I did change the color a bit in Photoshop using Hue/Saturation. I also changed the BLENDING MODE. I used the DARKEN blending mode.
4. I wanted a stream coming up the left side. You can see a little of that but I wanted more water. I found a stream online and put that in my composition.
Okay, I don't know why I put in fruit. I usually put in flowers. At least I didn't put in a fish. Well, actually, I DID put in a fish, but I took it out. 
