U sing a static site generator usually involves text files with very little formatting. For this to work, you need to have your content in a format that the system can use. As you have seen earlier, most systems will accept Markdown as the format for your source text.
For the configuration and such, you will need to use what others have written and adjust it. In these files, the format is YAML, JSON or TOML. Most readers should know these formats since we use them extensively for many things. With that said, the formats are easy to learn.