What is the best way to create my own images that I wish to import into a Socratic answer?
The first criterion would simply be what is allowed/possible to post. The second is what type of graphic you produce.
I find the jpeg to be the easiest in terms of production, portability and reasonable size. HOW to create images depends on the complexity of your image.
I find that one of the easiest ways to make combined (photo/clip art/) graphics is to make either a "presentation" slide or a "Word" page with everything imported/pasted/written/drawn. Those formats/programs usually have an "export" or similar function that allow you to make the entire page a single image. Those are usually jpg or .pdf files that can be loaded to Socratic.