How does one get into "training a model"? What are requisite skills for such a task?

ELI5 please. How would someone go from no software engineering expertise, to making and training models for a specific niche function? I get training image and language software just means feeding the respective widely available AI models, image and language data, but how about for other functions? Like how does one train an AI for a specific task like say, analyzing a particular topic or dataset?

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