Thanks for the compliment. Your question is most welcome. The answer is however not mystical. Do you want the long answer or the short answer?
It is no big secret - I use PaintDotNet for making images in Windows. If you have specific questions on how the particular image was created - please feel free to ask.
The owner of the application (~7MB), Mr. Brewster, previously worked for Microsoft. He has done a very brilliant job at demonstrating to us what can be done with the DotNet framework. And then he allows us to use it for fee. However… please consider making a donation.
Not only is the install footprint small and it is free, it has the ability to use layers.
Other free image creation packages to look at…